Sabre Perkins still overheating
- Thread starter stuartwineberg
- Start date
stuartwineberg
Well-known member
Bought!
Good idea and ordered. Silly question but is the spot temperature on the outside of the block the same temp as the one indicated on the gauges (assuming they are accurate)?
Good idea and ordered. Silly question but is the spot temperature on the outside of the block the same temp as the one indicated on the gauges (assuming they are accurate)?
Latestarter1
New member
Stuart
Front of cylinder head is correct place, not the bock, the little cheapo laser guns are real accurate, used to cost about £75, now peanuts.
Just a few thoughts for what they are worth. From memory your thermostat modulates in the range of 83-95 C. If motors operating at a TRUE 85 C them thermostat barely open. However you are correct to be concerned if temp gauge moves like the tacho when you give motor the beans.
Heat exhanger on Perkins Sabre is a bit marginal, has it been completely cleaned? I use ultrasonic cleaner to go the job.
We all crab Sherwood raw water pumps, however they do have 1/8th NPT test ports on them where you test for inlet restriction and pump output pressure. Not sure what test points your Jabsco has if any, however you want to see around 15 but no more than 20 psi on pressure side of the pump and about 5 psi at the 1/8th tapping on the gear cooler for your stern gland, pretty much the end of the cooling water food chain. Any more than 20 psi at the pump indicated that your cooling side is clagged up.
Just 500 or so hours seems very little time for wear in raw water pump, however you can always side for side the pumps to eliminate this one.
Good luck
nedmin
Active member
Re: water pump wear,I,ve done about 1300hrs and pump works fine altho I have changed wear plates and cam.This is using the boat in very silted waters.Rivers Trent ,Humber and Ouse.Have you changed the sensors from one engine to the other to compare?
nedmin
Active member
Another thought,can you put a bucket under the exhaust outlets and time how long it fills,then try the other engine,or if not could you do where it comes out the engine? If you do dont gas yourself!!
stuartwineberg
Well-known member
Thanks
I'm over an hour from the boat and sadly back at work - hoping to get down tomorrow to take a look - if not next week. Please don't take lack of feedback as lack of interest by me in your ideas - keep em coming
I'm over an hour from the boat and sadly back at work - hoping to get down tomorrow to take a look - if not next week. Please don't take lack of feedback as lack of interest by me in your ideas - keep em coming
stuartwineberg
Well-known member
Thanks also
Thanks for the laser advice - waiting for uncle Ebay to deliver.
Exchanger completely removed, core taken out and washed and each channel rodded out with soft wire, ditto with the oil cooler. To be honest both were clear apart from bits of loose powder - no solid chalking up at all. VP had already serviced the heat exchanger the year before. Putting pressure gauges on the pump is a bit outside my very amateur capability but I will have a look at the rwp to see if it has ports. I dont think the stern gland has a cooler - its a traditional stuffing box. the raw water circuit goes - inlet, pump, air charge cooler, gearbox oil cooler, exchanger, exhaust elbow and out. the turbo is dry
You describe the core problem exactly when you say the temp moves like the tacho when I open the throttle. However there is a lag of about half to a minute when I open up before the temp goes from about 83 to 90 but it drops back almost immediately when I throttle back
Switching the pumps is last resort as they are not simple bolt ons as I see it. gear driven and I think you have to replace some seals if you take them off as they are an interference fit (apols if this is gibbersih - as i say I am an amateur)
Thanks for the laser advice - waiting for uncle Ebay to deliver.
Exchanger completely removed, core taken out and washed and each channel rodded out with soft wire, ditto with the oil cooler. To be honest both were clear apart from bits of loose powder - no solid chalking up at all. VP had already serviced the heat exchanger the year before. Putting pressure gauges on the pump is a bit outside my very amateur capability but I will have a look at the rwp to see if it has ports. I dont think the stern gland has a cooler - its a traditional stuffing box. the raw water circuit goes - inlet, pump, air charge cooler, gearbox oil cooler, exchanger, exhaust elbow and out. the turbo is dry
You describe the core problem exactly when you say the temp moves like the tacho when I open the throttle. However there is a lag of about half to a minute when I open up before the temp goes from about 83 to 90 but it drops back almost immediately when I throttle back
Switching the pumps is last resort as they are not simple bolt ons as I see it. gear driven and I think you have to replace some seals if you take them off as they are an interference fit (apols if this is gibbersih - as i say I am an amateur)
stuartwineberg
Well-known member
Sounds a cold job!
Might just be doable as the outlets are almost at water level but I can reach them easily from the bathing platform - another good idea - thanks
Might just be doable as the outlets are almost at water level but I can reach them easily from the bathing platform - another good idea - thanks
david_bagshaw
Well-known member
the water flow rate needs to be checked while under top/ high load, as the exhaust pressure is highest then, causing the greatest back pressure on the water pump. Idle / high idle would not be conclusive..
I have had differential wear on a twin installation, probably caused by the elbow on the pump, when the lesser worn one had straight connectors.
If not mentioned before is there a sufficient blead hole / jiggler in the thermostat, to ensure an adequate flow around the wax chamber in the early opening up phase?
How long have you run at the hot upper end? long enough for it to stablise?
are you running at equal boost levels, as boost pressure is a good measure of power being pulled from the engine?
I have had differential wear on a twin installation, probably caused by the elbow on the pump, when the lesser worn one had straight connectors.
If not mentioned before is there a sufficient blead hole / jiggler in the thermostat, to ensure an adequate flow around the wax chamber in the early opening up phase?
How long have you run at the hot upper end? long enough for it to stablise?
are you running at equal boost levels, as boost pressure is a good measure of power being pulled from the engine?
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nedmin
Active member
Not necessarily depends on the pipework arrangement a high exhaust pressure could help the pump due to venturi action.
Jim@sea
Well-known member
Do Perkins have Wet Liners like Cummins and Zetor. We had a tractor whose engine overheated. It turned out that the Cylinder Bore was porous. Have you done a compression check.
omega2
Active member
Just remembered an incident that happened to a mate of mine, he overheated because the flexible hose at the intake side of the jabsco collapsed due to suction pressure of pump, we got round it by "lining" the hose with a piece of steel pipe.
stuartwineberg
Well-known member
Improving
Went out yesterday for a long run and the temp only went up very slowly - by the time we got back from Cowes to Gosport - 2200 revs all the way the port engine was on 90 and the starboard on about 86. My money is starting to be on some sort of crud in the intake that was perhaps starting to be worn away by the high speed water flow. I really appreciate all the input from the forum but if she continues to stabilise I will leave it as is until she comes out in April and then really ream out the intakes from the outside. If the overheating comes back I will return to your excellent advice. The ebay thermometer arrived today so will check whether the temp is real next time I go out
Thanks again and will keep updating as soon as I have more info
Went out yesterday for a long run and the temp only went up very slowly - by the time we got back from Cowes to Gosport - 2200 revs all the way the port engine was on 90 and the starboard on about 86. My money is starting to be on some sort of crud in the intake that was perhaps starting to be worn away by the high speed water flow. I really appreciate all the input from the forum but if she continues to stabilise I will leave it as is until she comes out in April and then really ream out the intakes from the outside. If the overheating comes back I will return to your excellent advice. The ebay thermometer arrived today so will check whether the temp is real next time I go out
Thanks again and will keep updating as soon as I have more info
david_bagshaw
Well-known member
dont forget sea water is cooler at this time of year.
seem to remember extra 3 deg c differental = twice the energy exchange.
seem to remember extra 3 deg c differental = twice the energy exchange.
stuartwineberg
Well-known member
stuartwineberg
Well-known member
Update
Fitted new thermostat today, checked exhaust elbow - all OK, checked inlet raw water flow by removing hose between strainer and engine when on the marina with engines off - seemed fine. Hoses seem in good order - no sign of internal collapsing. took her out - no change - gradual increase on port engine. My new laser thermomenter tells me the sboard engine is running at 86 and the port engine was up to 94 when I lost my nerve and throttled back - instantly back to about 82. I reckon I was seeing steam out of the exhaust at that point. BTW - what is a proper running temp for these engines?
The manual says the thermostat starts to open at 78/82 and is fully open at 92/96 - am I bottling out too soon? it's a waxstat stamped 80 degrees - sabre perkins part (only a tenner - thought that was reasonable)
Am now starting to think about the raw water pump. Its tricky to get to on the engine but the exploded diagram in the manual shows that it has a seperate wear plate and cam so at least I shoudl be able to replace these rather than get a new pump. Does the fresh water pump ever fail on these?
Thoughts please
Fitted new thermostat today, checked exhaust elbow - all OK, checked inlet raw water flow by removing hose between strainer and engine when on the marina with engines off - seemed fine. Hoses seem in good order - no sign of internal collapsing. took her out - no change - gradual increase on port engine. My new laser thermomenter tells me the sboard engine is running at 86 and the port engine was up to 94 when I lost my nerve and throttled back - instantly back to about 82. I reckon I was seeing steam out of the exhaust at that point. BTW - what is a proper running temp for these engines?
The manual says the thermostat starts to open at 78/82 and is fully open at 92/96 - am I bottling out too soon? it's a waxstat stamped 80 degrees - sabre perkins part (only a tenner - thought that was reasonable)
Am now starting to think about the raw water pump. Its tricky to get to on the engine but the exploded diagram in the manual shows that it has a seperate wear plate and cam so at least I shoudl be able to replace these rather than get a new pump. Does the fresh water pump ever fail on these?
Thoughts please
stuartwineberg
Well-known member
Thanks Jim
If things are at this stage then I am completely out of my depth - so I will pass on that question for the moment but thanks for the idea anyway. From what I have read elsewhere the issue on diesels isn't compression its blow back - sorry if that isnt exactly the right term
If things are at this stage then I am completely out of my depth - so I will pass on that question for the moment but thanks for the idea anyway. From what I have read elsewhere the issue on diesels isn't compression its blow back - sorry if that isnt exactly the right term
longjohnsilver
Well-known member
Even though the flow looked fine there could still be a restriction, don't forget that the pump will be trying to pull through significant volumes of water as load increases. I'd still try the reverse flush with the dinghy pump, easy to do and nothing to lose. With mine I also had what I thought was a good water flow at rest but there was a blockage which prevented a good flow when under load.
david_bagshaw
Well-known member
We have the ford sabre 150 x 2 ,. different engine, however same principals, v similar pumps
Are you running at equal boost pressures if not set engine speeds to get equal boost, & therefore equal power supply.
on these the thermostat opens one side, and at the same time blocks off another passage. this type cant be removed and the engine run safely at higher powers. If the perkins sabre is different , try running without t stat.
raw water pump is easyly done quite straight forward. at the same time replace the seal, on ours it is a carbon faced one side and ceramic the other. Definately replace the cam, back plate & impeller at the same time.
New impellers installed with worn plates take a long time to reach full efficiency, much longer than when all is replaced. not a problem at low engine power, but higher powers find the weaknesses. do the suction pipes have wire reinforcing to stop them collapsing with higher flows. are the pipes the correct size as indicated by sabres. Certain the sea cock is opening fully, not bunged with growths etc
Personally Iwould keep the power on a litttle longer, as t stst has to open fully, and it might not yet have done so. The fact it so quickly returns sounds like a blockage / back pressure issue. I take it the header tank doesnt bubble at higher power from lost combustion products. there is a tester avaailable to test for this.
If I had enough hose I would piut the water out put from one engine to the exhaust of the other, in both cases, and carefully start both at the same time to avoid engine flooding, then go for a spin. if no change ,revert & do the same for inlets. if no change revert, then swap sea water pumps engine to engine.
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volvopaul
Well-known member
As you have now given us some readings from your hand held thermometer from the area where the temp sender is that good, but you have only really looked at the hot area where the sender is.
The idea of checking temperatures in your case is to gather data from the sea trial, return and take stock of what data you have, then an answer to the problem can be found.
You really need to take more readings in other areas of the engines cooling system, and exhaust system in order to find whats working to its capacity and whats not working, thats where the answer to the problem will lie.
As you say you saw steam that could be from different reasons, 1 actuall heat created from lack of sea water in the exhaust elbow as thats the hottest area of the engine near the turbo. 2 the raw water actually really hot, up to somewhere near the same temp as the fresh water, if thats the case the heat exchanger is doing its job but the overheat is actually true temp in the system due to another component not doing its job. 3 a very high exhaust temp which is transfering back into the engine right through the system, if thats the case it needs sorting before you end up damaging the valves, turbo and piston tops.
Id have a sea trial with me or who ever that can go about diagnosing your problem with the data gathered.
As the sea temp is quite low the raw water side should work really well but there could be a massive imbalance between the two due to component failure somewhere on the engine, as ive said gathering the right data is the answer, as ive said in a previous volvo related post its a bit like pinning the tail on the donkey through a welding mask.
Ive just been talking to a Broom 41 owner with the 300 mti engines, hes just had a 24k rebuild by a well known Perkins agent, all because of a raw water problem not related to impeller failure, his exhaust manifold resembled a cullender from the heat.