KAD44 turbo boost issues

[Dessie]

Hi All

Hoping I can get some help here with a problem after my recent service.

We have a Cranchi 39 Endurance running a pair of KAD44s. Right after being relaunched after the service, we experienced a problem where running at 2800-3000 revs we get some surging with the revs dropping off for a second or two as the compressor kicks in suggesting a boost issue. The typical boat working absolutely fine before heading into a service.

During the service we had the Port aftercooler cleaned as a new turbo was fitted during last season on the mooring and engineer said the turbo seal was leaking oil so marked the aftercooler to be cleaned at next service, all good so far.

Anyway, engineers came out for a sea trial yesterday and are saying this is normal and I should get used to it, that 2800 is close to the tipping over point where the turbo is just generating enough boost so any extra load on the engine will mean the compressor kicks in and that is the surge I am feeling, also added that I am running a classic after all, seas were flat so not sure where the extra load happened. This doesn't sit well as we don't get a kick from the compressor, we get a drop off in power first. Engines reached 3600 at WOT without the surging (full fuel and water tanks) and engineer said if we had a turbo problem then we wouldn't reach 3600. We can't go around at WOT and 2800/3000 is our cruising speed especially with the seas we get around here.

Checking for air leaks around the pipes we are getting nothing, having seen the aftercooler housing and noting the paint on the top bolts look untouched, versus the back bolts coming from the turbo, I asked how they removed the cassette and they said it was from the back which I thought was impossible as thought it had to be removed from the top "YouTube", anyway trusted them on this point, however I am wondering if this could possible mean something wrong with the seals in the aftercooler especially water bypassing the cooling tubes and the air is not being cooled causing the issue.

Logic would dictate the issue showed itself after something was done to the aftercooler, however we have had a progressive issue with the starboard engine taking longer to start over the season with the engineer suggesting its the low pressure fuel pump allowing fuel to drain back in the system so the engine needs to be primed each time. New fuel pump on order.

The classic quandary, is it fuel or air causing the issue and head is saying I should get the aftercooler removed and checked. Can this be done on the mooring, or is this a haul out again?

Video on YouTube if this helps.

Many thanks

 

[Mr Googler]

It is impossible to remove the after cooler stack from any other way than from the top. Defo sounds like an air leak. Check again but just on cold start up so the compressor is running. Makes it much easier to find leaks. Volvopaul trick that one Have a good feel around all areas of the after cooler

 

[Mr Googler]

Forgot to ask….are you making full revs at WOT? 3800 rpm

 

[volvopaul]

Hi All

Hoping I can get some help here with a problem after my recent service.

We have a Cranchi 39 Endurance running a pair of KAD44s. Right after being relaunched after the service, we experienced a problem where running at 2800-3000 revs we get some surging with the revs dropping off for a second or two as the compressor kicks in suggesting a boost issue. The typical boat working absolutely fine before heading into a service.

During the service we had the Port aftercooler cleaned as a new turbo was fitted during last season on the mooring and engineer said the turbo seal was leaking oil so marked the aftercooler to be cleaned at next service, all good so far.

Anyway, engineers came out for a sea trial yesterday and are saying this is normal and I should get used to it, that 2800 is close to the tipping over point where the turbo is just generating enough boost so any extra load on the engine will mean the compressor kicks in and that is the surge I am feeling, also added that I am running a classic after all, seas were flat so not sure where the extra load happened. This doesn't sit well as we don't get a kick from the compressor, we get a drop off in power first. Engines reached 3600 at WOT without the surging (full fuel and water tanks) and engineer said if we had a turbo problem then we wouldn't reach 3600. We can't go around at WOT and 2800/3000 is our cruising speed especially with the seas we get around here.

Checking for air leaks around the pipes we are getting nothing, having seen the aftercooler housing and noting the paint on the top bolts look untouched, versus the back bolts coming from the turbo, I asked how they removed the cassette and they said it was from the back which I thought was impossible as thought it had to be removed from the top "YouTube", anyway trusted them on this point, however I am wondering if this could possible mean something wrong with the seals in the aftercooler especially water bypassing the cooling tubes and the air is not being cooled causing the issue.

Logic would dictate the issue showed itself after something was done to the aftercooler, however we have had a progressive issue with the starboard engine taking longer to start over the season with the engineer suggesting its the low pressure fuel pump allowing fuel to drain back in the system so the engine needs to be primed each time. New fuel pump on order.

The classic quandary, is it fuel or air causing the issue and head is saying I should get the aftercooler removed and checked. Can this be done on the mooring, or is this a haul out again?

Video on YouTube if this helps.

Many thanks

You sure have some lying engineers there for sure , you cannot remove the core without removing the lid.
Id certainly question where you had your turbo repaired if it’s had a welded insert fitted then get it taken off and done properly, the surging is due to lack of boost from the turbo , it’s simply not giving boost to match the supercharger when the super charger cuts out , if you have no air leaks on the pipe from the turbo to the intercooler check the joint between the intercooler and the inlet manifold, it’s gasket sealant no actual gasket there , also the inlet manifold to the head has no gasket just sealant and does break down after time .

 

[volvopaul]

To add , next time you do a sea trial disconnect the sync button that will then show you if the other engine has a lot more power , doing what you did won’t show how bad the lame engine is because the edc is trying to match the revs on each engine .

 

[Dessie]

Forgot to ask….are you making full revs at WOT? 3800 rpm

Thanks for your earlier comment will try that tomorrow. We are making 3600 but have full fuel and water as well as full dinghy garage with paddle boards etc. I will try and feel around the aftercooler tomorrow, been checking around the turbo connections but not the atercooler.

 

[Dessie]

To add , next time you do a sea trial disconnect the sync button that will then show you if the other engine has a lot more power , doing what you did won’t show how bad the lame engine is because the edc is trying to match the revs on each engine .

Thanks will do that. Sounds an obvious thing to do now you say it. I'll also check the joints around the inlet manifold and the horn connecting the turbo to the intercooler with a cold start.

 

[Dessie]

You sure have some lying engineers there for sure , you cannot remove the core without removing the lid.
Id certainly question where you had your turbo repaired if it’s had a welded insert fitted then get it taken off and done properly, the surging is due to lack of boost from the turbo , it’s simply not giving boost to match the supercharger when the super charger cuts out , if you have no air leaks on the pipe from the turbo to the intercooler check the joint between the intercooler and the inlet manifold, it’s gasket sealant no actual gasket there , also the inlet manifold to the head has no gasket just sealant and does break down after time .

Thanks Paul, I climbed in the engine bay and checked the intercooler to the inlet manifold and also the horn from the turbo to the intercooler and behold I have a leak. This is the compressor from a cold start and using the trusty washing up liquid shows I am leaking around the bolts holding the horn section to the intercooler. I don't know why they took it all to bits if you extract the core from the top anyway.

I will be calling the engineers next week.

Thank you very much for your help on this and to Mr Googler. @Mr Googler

Best
Steve

 

[Dessie]

It is impossible to remove the after cooler stack from any other way than from the top. Defo sounds like an air leak. Check again but just on cold start up so the compressor is running. Makes it much easier to find leaks. Volvopaul trick that one Have a good feel around all areas of the after cooler

Thank you loads for your help on this.

I did climb into the engine bay and my wife kindly ran the engine up so I could record this picture of the bell or horn from the turbo into the intercooler. Brushed some washing up liquid and our comes the air from around the bolts, using the cold start on the compressor.

Many thanks again.
Best regards
Steve

 

[Mr Googler]

I see what they have done…..taken the back off the intercooler housing to clean only the air side of the cooler. Absolute clowns.

Where have they cleaned the contamination too…..towards your engine!

Remove the tube stack and do it properly. I’d honestly get someone else to do the work and send the original “mechanic” the bill!.

 

[Mr Googler]

As you can see….the fins that the air passes through are very close together hence…it needs to be removed for cleaning so all the oil can drain away from the fins

It’s all very delicate too. Get someone else to remove and inspect. Easy to damage and they are £1.8k to replace

 

[BruceK]

Anyway, engineers came out for a sea trial yesterday and are saying this is normal and I should get used to it, that 2800 is close to the tipping over point where the turbo is just generating enough boost so any extra load on the engine will mean the compressor kicks in and that is the surge I am feeling, also added that I am running a classic after all, seas were flat so not sure where the extra load happened. This doesn't sit well as we don't get a kick from the compressor, we get a drop off in power first. Engines reached 3600 at WOT without the surging (full fuel and water tanks) and engineer said if we had a turbo problem then we wouldn't reach 3600. We can't go around at WOT and 2800/3000 is our cruising speed especially with the seas we get around here.

Actually your engineer is correct. As this is a fully blown engine any reduction in turbo boost effiency will cause a lag in handover and if the boat is loaded and struggling then the parasitic drag caused by spooling up the supercharger while at such high revs will cause a quite significant power drop then surge. The real question here is there is a small transitional gap between where the supercharger should kickout unless in kickdown mode and that is well enough below the revs you are talking about unless you are in kick down mode where the surpercharger will take you right up to the 3k odd mark. SO if your supercharger is kicking in at or arount 3k revs then you are probably not cruising but in kickdown mode and should look at why your engine is loaded so heavily. Age, dirty bottom, props, weight, lazy pair are all potential candidates alongside those already proposed and yes most of that can very easily happen between seasons.

As for your engineer cleaning just the air passages, well taht is where the oils is. If it was in the coolant well you'd be in serious shit and although the cleaning method is unorthodox is not actually incorrect.
Be careful of internet witch hunts on the forum. Loads of very knowledgeable folk but they arent actually there and acctually working on the problem. I would work with the mechanic. Not all issues are solved first time round. If only boat life were that goddamn simple.

Personally I would start with a boost check. Plenty threads here on how that is done and I am surprised no one mentioned that

 

[BruceK]

(please excuse the poor spelling and grammar - I am a bit wobbly in the head these days especially when it comes to typing)

 

[petem]

(please excuse the poor spelling and grammar - I am a bit wobbly in the head these days especially when it comes to typing)

Actually your engineer is correct. As this is a fully blown engine any reduction in turbo boost effiency will cause a lag in handover and if the boat is loaded and struggling then the parasitic drag caused by spooling up the supercharger while at such high revs will cause a quite significant power drop then surge. The real question here is there is a small transitional gap between where the supercharger should kickout unless in kickdown mode and that is well enough below the revs you are talking about unless you are in kick down mode where the surpercharger will take you right up to the 3k odd mark. SO if your supercharger is kicking in at or arount 3k revs then you are probably not cruising but in kickdown mode and should look at why your engine is loaded so heavily. Age, dirty bottom, props, weight, lazy pair are all potential candidates alongside those already proposed and yes most of that can very easily happen between seasons.

As for your engineer cleaning just the air passages, well taht is where the oils is. If it was in the coolant well you'd be in serious shit and although the cleaning method is unorthodox is not actually incorrect.
Be careful of internet witch hunts on the forum. Loads of very knowledgeable folk but they arent actually there and acctually working on the problem. I would work with the mechanic. Not all issues are solved first time round. If only boat life were that goddamn simple.

Personally I would start with a boost check. Plenty threads here on how that is done and I am surprised no one mentioned that

I was going to mention a boost check but was on holiday!

Three ways of doing this:

1) Get a VP engineer to plug in Vodia.
2) Fit a YachtDevices gateway.
3) Custom boost gauge.

 

[Dessie]

Actually your engineer is correct. As this is a fully blown engine any reduction in turbo boost effiency will cause a lag in handover and if the boat is loaded and struggling then the parasitic drag caused by spooling up the supercharger while at such high revs will cause a quite significant power drop then surge. The real question here is there is a small transitional gap between where the supercharger should kickout unless in kickdown mode and that is well enough below the revs you are talking about unless you are in kick down mode where the surpercharger will take you right up to the 3k odd mark. SO if your supercharger is kicking in at or arount 3k revs then you are probably not cruising but in kickdown mode and should look at why your engine is loaded so heavily. Age, dirty bottom, props, weight, lazy pair are all potential candidates alongside those already proposed and yes most of that can very easily happen between seasons.

As for your engineer cleaning just the air passages, well taht is where the oils is. If it was in the coolant well you'd be in serious shit and although the cleaning method is unorthodox is not actually incorrect.
Be careful of internet witch hunts on the forum. Loads of very knowledgeable folk but they arent actually there and acctually working on the problem. I would work with the mechanic. Not all issues are solved first time round. If only boat life were that goddamn simple.

Personally I would start with a boost check. Plenty threads here on how that is done and I am surprised no one mentioned that

Thanks Bruce, our plan is to work with the engineers and get this fixed, already in touch with them and agreed we will make a plan. Boat was out of the water for its service, so clean bottom and props and was working absolutely fine prior to the service with the issue happening straight after getting back in the water, so logic is to start with the one thing that was disturbed on the engine with the intercooler other than a standard service with filters and belts. They have to reseal the back part anyway.

Fingers crossed that will be the problem solved.

 

[Dessie]

Hi All

Thought I would provide an update to the turbo boost issue where the revs on my port engine blips losing revs, compressor kicks in and then back up with the turbo. All your comments have been very helpful. Brief loss of turbo boost was the thought.

Right, so first job was the Marine firm removed the aftercooler housing and did the job properly, taking the aftercooler core out the top of the casing and cleaning properly before refitting with new gaskets as well as sealing up the leaking aftercooler housing. After relaunching and testing for any air leaks from the airfilter all the way to the engine intake and finding leaks around the plastic Y valves underneath the rubber gasket near the gate valve, I replaced both of these with new as well as new rubber gators and jubilee clips where they attach to the plastic elbow into the turbo. Tested and zero air leaks.

Unfortunately, problem still existed so onto plan B, replace everything. Theory was now the starboard turbo may be having issues with blow back or leaking exhaust elbow, causing the port engine to get extra load, hence the momentary drop in revs as port engine compensated for starboard. Ok engineer removed the starboard elbow and yes the turbo exhaust side was quite coked up with soot, still spun freely and gap in the blades didn't look too bad. Turbo was 5 years old so we decided to replace it with new as well as two new exhaust elbows as well as a bit of corrosion, replacing the port elbow at the same time, what the hell, keep going. Port turbo was new last May 2022 and was spinning freely on both exhaust and compressor side. Oh we also replaced with a full set of new Volvo duo props on both sides. Existing props were 5 years old and were due to be replaced anyway, same size, B4s, engine revs to its 3800 level so stick with what we know.

We used the boat for three times after this without a single blip of the port engine, everything performing well with the new props, jumping on the plane and singing sweetly. However come the fourth time we take her out, we start getting this sporadic blip again. Marine engineer came out for a sea trial yesterday and this time, the first time revs dipped was at 1000 rpm as we were heading out the fairway, this is 700 odd revs below where the compressor should kick in and feels like the engine cuts out for a split second before rpms recover, this dipping occurred sporadically all the way through the cruise speed at 3000 rpm to 3400 high speed cruise.

We have replaced everything mechanically that we can, unless the year old port turbo is at fault, but as mentioned this spins easily both air side and exhaust side, no gaps in the fins to the wall and why would this occur at 1000 rpm. Is there anything else mechanically we should be looking at.

Our mechanic has at our suggestion, replaced everything that can be done as we said to throw the lot at it rather than piece by piece. He now is thinking this could be an electrical problem. I asked if it could be fuel and he replied no, the engine is cutting out and back in immediately, if fuel he said it would be a gradual loss before recovery not the instant blip we are seeing.

Anyway, his next step, he is going to check the speed sensor in the timing gear housing, apparently a pain to get to in an outdrive boat and use some contact cleaner on the electric plugs in case of a dry connection. I've read comments on this thread about the turbo boost sensor on the airside engine intake can give false readings. Given the initial problem was cleaning the aftercooler core whilst in the aftercooler housing so blowing crud through to the engine side, I wondered if this could have shoved some crud up into the plastic tube or to the turbo boost sensor itself.

We have the KAD44P-B EDC 260HP engines with DP290 legs, is there any other sensor like on the high pressure fuel pump as another comment was the proximity switch on the fuel pump?

Sorry for the long message, but I guess I am looking for ideas now. Can this be a fuel issue, or does the fact it's a momentary blip in the revs mean it's likely sensor or electrical?

 

[Dessie]

To add , next time you do a sea trial disconnect the sync button that will then show you if the other engine has a lot more power , doing what you did won’t show how bad the lame engine is because the edc is trying to match the revs on each engine .

Hi Paul

Apols for the long reply, but thought I would add an update to the ongoing fix to our boat.

This was the turbo boost issue where the revs on my port engine blips losing revs, compressor kicks in and then back up with the turbo. All your comments have been very helpful. Brief loss of turbo boost was the thought.

Right, so first job was the Marine firm removed the aftercooler housing and did the job properly, taking the aftercooler core out the top of the casing and cleaning properly before refitting with new gaskets as well as sealing up the leaking aftercooler housing. After relaunching and testing for any air leaks from the airfilter all the way to the engine intake and finding leaks around the plastic Y valves underneath the rubber gasket near the gate valve, I replaced both of these with new as well as new rubber gators and jubilee clips where they attach to the plastic elbow into the turbo. Tested and zero air leaks.

Unfortunately, problem still existed so onto plan B, replace everything. Theory was now the starboard turbo may be having issues with blow back or leaking exhaust elbow, causing the port engine to get extra load, hence the momentary drop in revs as port engine compensated for starboard. Ok engineer removed the starboard elbow and yes the turbo exhaust side was quite coked up with soot, still spun freely and gap in the blades didn't look too bad. Turbo was 5 years old so we decided to replace it with new as well as two new exhaust elbows as well as a bit of corrosion, replacing the port elbow at the same time, what the hell, keep going. Port turbo was new last May 2022 and was spinning freely on both exhaust and compressor side. Oh we also replaced with a full set of new Volvo duo props on both sides. Existing props were 5 years old and were due to be replaced anyway, same size, B4s, engine revs to its 3800 level so stick with what we know.

We used the boat for three times after this without a single blip of the port engine, everything performing well with the new props, jumping on the plane and singing sweetly. However come the fourth time we take her out, we start getting this sporadic blip again. Marine engineer came out for a sea trial yesterday and this time, the first time revs dipped was at 1000 rpm as we were heading out the fairway, this is 700 odd revs below where the compressor should kick in and feels like the engine cuts out for a split second before rpms recover, this dipping occurred sporadically all the way through the cruise speed at 3000 rpm to 3400 high speed cruise.

We have replaced everything mechanically that we can, unless the year old port turbo is at fault, but as mentioned this spins easily both air side and exhaust side, no gaps in the fins to the wall and why would this occur at 1000 rpm. Is there anything else mechanically we should be looking at.
Our mechanic has at our suggestion, replaced everything that can be done as we said to throw the lot at it rather than piece by piece. He now is thinking this could be an electrical problem. I asked if it could be fuel and he replied no, the engine is cutting out and back in immediately, if fuel he said it would be a gradual loss before recovery not the instant blip we are seeing.

Anyway, his next step, he is going to check the speed sensor in the timing gear housing, apparently a pain to get to in an outdrive boat and use some contact cleaner on the electric plugs in case of a dry connection. I've read comments on this thread about the turbo boost sensor on the airside engine intake can give false readings. Given the initial problem was cleaning the aftercooler core whilst in the aftercooler housing so blowing crud through to the engine side, I wondered if this could have shoved some crud up into the plastic tube or to the turbo boost sensor itself.

We have the KAD44P-B EDC 260HP engines with DP290 legs, is there any other sensor like on the high pressure fuel pump as another comment was the proximity switch on the fuel pump?

Sorry for the long message, but I guess I am looking for ideas now. Can this be a fuel issue, or does the fact it's a momentary blip in the revs mean it's likely sensor or electrical?

 

[volvopaul]

Surging at high rpm is lack of fuel at the pump , have you removed the lift pump to check if the arm has detached from the pump , a common problem as engine will suck it’s own fuel from the vane pump once running .

Check the stop solenoid spring as at high rpm the stop plunger can be sucked down if the spring is weak , this blocks the fuel port into the cam head .

 

[QBhoy]

That’s more like a fuel issue I’d say. A boost issue isn’t as suddenly detrimental as that usually. But the mention of the supercharger having to come back in higher up ascending rpms, also usually suggests a turbo issue or lack of ability. Perhaps you have a boost leak somewhere?…but without reading all through the previous comments and just watching that video…I’d have had money on that being a fuel starvation issue. Especially at those rpms. Perhaps even an electrical issue, just with the behaviour there. Almost like a stop solenoid or electronic intervention there. Seems too sudden or rhythmic to be a boost issue. Not sure.

 

[Dessie]

That’s more like a fuel issue I’d say. A boost issue isn’t as suddenly detrimental as that usually. But the mention of the supercharger having to come back in higher up ascending rpms, also usually suggests a turbo issue or lack of ability. Perhaps you have a boost leak somewhere?…but without reading all through the previous comments and just watching that video…I’d have had money on that being a fuel starvation issue. Especially at those rpms. Perhaps even an electrical issue, just with the behaviour there. Almost like a stop solenoid or electronic intervention there. Seems too sudden or rhythmic to be a boost issue. Not sure.

Thanks for the reply, I realised I never did close off this thread with the thing that fixed that blipping boost pressure. After replacing loads of parts, Turbo, two exhaust elbows, the plastic Y pieces, cleaning the aftercooler properly that didn't resolve the issue, the problem we think was a dry connection. Simply a can of contact cleaner and unplugging/plugging every sensor and main harness a few times and the problem disappeared.

Parts were due to be replaced anyway, but was blinded that it had to be a mechanical problem, when the first attempt should have been checking the connections with some contact spray.

Thanks for your response, much appreciated.