Volvo TAMD 74P boost pressure problem

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koisteve

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I think I have lost boost pressure as the engine won't rev above 11-1200 revs when under load. All relevant filters have been replaced. In neutral the turbo kicks in and it revs to 2000, the max the edc's allow. I was told to look for a blown gasket or sealing rings on the input side but couldn't find anything wrong. So I decided to remove the waste gate valve (I've had the broken pipe/excess boost pressure before). The waste gate valve itself had black soot over 1/3 of it's seating area so I had a gentle scrape on the seat itself, thinking it was soot, but it appears the metal seat is rusting away. The KKK turbo part number 3802139 OEM3837691 has been removed and my questions are:-
1 - Will this be the cause of the lack of boost pressure?
2 - Is there a valve seat in the turbo housing that has disappeared or will it need a new exhaust housing as these don't appear to be available?
3 - Recommendations for good turbo specialists? Boat based in Portsmouth area.
Many thanks
 
The rpm speed attained is a classic sign that the boost sensor has failed.
It's the only sensor that can fail to work but not give a fault code.

It's inside the ecu behind the plate cover.
You can remove it and try to dry it out as it fills with condensation which is the cause of failure.
 
volvopaul said:
The rpm speed attained is a classic sign that the boost sensor has failed.
It's the only sensor that can fail to work but not give a fault code.

It's inside the ecu behind the plate cover.
You can remove it and try to dry it out as it fills with condensation which is the cause of failure.
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Thank you VP for responding, your Volvo experience is showing through on these boards! When I had the excess boost pressure problem and fixed the broken pipe, the fault code wouldn't go away. It was suggested to me the boost sensor might be playing up. I regularly drain these pipes now, but haven't done the "drill the hole in the nut" mod cos I'm not sure how small it should be and squirted WD40 up the pipe. Low and behold problem cleared. I was thinking that, even if I have the turbo rebuilt, this fault would still exist. But I thought the sensor would only show excess pressure problems not lack of boost problems. So I will go down the sensor route as well, I can't afford to keep buying these bits so I swap from engine to engine. But definitely the waste gate seal is shot, looks like water pitting on what's left of it. Supposed to be on my holidays now, but turbo is in the back of my van, just wondering where I could take it to get an opinion? Don't think the turbo is shot, just the waste gate valve seat. Maybe I'll slam it all back and have a displacement speed holiday!! Thanks for all your input on this board. On a downer at the moment because the prices are hurting me. On a lighter note we've done Gaffers for 7 years now so probably seen you come in/go out. Looks like you're a socialising bunch and would like to catch you for a beer on your next meet. Promise not to talk about engine problems! Only joined the board today and noticed that Piers is here as well. He's a experienced Guernsey boater and a really nice chap, check him out if you're over that way.
 
koisteve said:
Thank you VP for responding, your Volvo experience is showing through on these boards! When I had the excess boost pressure problem and fixed the broken pipe, the fault code wouldn't go away. It was suggested to me the boost sensor might be playing up. I regularly drain these pipes now, but haven't done the "drill the hole in the nut" mod cos I'm not sure how small it should be and squirted WD40 up the pipe. Low and behold problem cleared. I was thinking that, even if I have the turbo rebuilt, this fault would still exist. But I thought the sensor would only show excess pressure problems not lack of boost problems. So I will go down the sensor route as well, I can't afford to keep buying these bits so I swap from engine to engine. But definitely the waste gate seal is shot, looks like water pitting on what's left of it. Supposed to be on my holidays now, but turbo is in the back of my van, just wondering where I could take it to get an opinion? Don't think the turbo is shot, just the waste gate valve seat. Maybe I'll slam it all back and have a displacement speed holiday!! Thanks for all your input on this board. On a downer at the moment because the prices are hurting me. On a lighter note we've done Gaffers for 7 years now so probably seen you come in/go out. Looks like you're a socialising bunch and would like to catch you for a beer on your next meet. Promise not to talk about engine problems! Only joined the board today and noticed that Piers is here as well. He's a experienced Guernsey boater and a really nice chap, check him out if you're over that way.
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Plenty of of turbo re-builders about who should be able to turn your unit around in three days.

However you may simply be addressing the problem not the cause. KKK make their turbine housings out of very poor materials which corrode like crazy at merest whiff of salt laden air. You need to look at the cause not the effect, well over 50% of marine exhaust systems I look at range from being at best poor to 'an accident waiting to happen'.
 
Latestarter1 said:
Plenty of of turbo re-builders about who should be able to turn your unit around in three days.

However you may simply be addressing the problem not the cause. KKK make their turbine housings out of very poor materials which corrode like crazy at merest whiff of salt laden air. You need to look at the cause not the effect, well over 50% of marine exhaust systems I look at range from being at best poor to 'an accident waiting to happen'.
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OP hasn't said what boat it is, I was going to ask him.

The wastegate seat does corrode allowing bypass, I have in past made an attempt to recut it in a machine shop by having an insert made, bit like a head valve seat. Far cheaper if the rest is ok than a new housing / turbo.
 
Thanks again everyone for responses, in summary I will look at the salt water intake and boost pressure valve. But the immediate problem is the waste gate valve seat. VolvoPaul's last response I feel is getting very close to the truth. I feel the turbo is running fine, more of an oily substance than usual on the intake side but I believe this is because the oil for the bearings is not being drawn out to the exhaust side, due to the waste gate valve issue. And now that I have scraped all the rust away it looks like the area was machined to take a valve seat, just like the engine valve seats. I have tried measuring the length of the waste gate valve compared to the depth of what is remaining of the valve seat and feel even with a bit of machining/polishing it could not make a good seal. I think on Monday I am going to take it to Turbo Dynamics for a first opinion since they do cast iron welding etc on site. Let me know if there is anywhere else that you could recommend. For clarity these TAMD 74P's have been shoe-horned into a Princess 435 and it performs very nicely. I believe this was done by RK Marine, with no expense spared. Luckily not at my expense!! We have had the boat for over 8 years now and have the ending hours from 250 to 950 and haven't needed to top up oil or water between annual services. Only problem ever being cracked boost pressure pipe. Any more ideas regarding the turbo seat etc much appreciated.
 
koisteve said:
Thanks again everyone for responses, in summary I will look at the salt water intake and boost pressure valve. But the immediate problem is the waste gate valve seat. VolvoPaul's last response I feel is getting very close to the truth. I feel the turbo is running fine, more of an oily substance than usual on the intake side but I believe this is because the oil for the bearings is not being drawn out to the exhaust side, due to the waste gate valve issue. And now that I have scraped all the rust away it looks like the area was machined to take a valve seat, just like the engine valve seats. I have tried measuring the length of the waste gate valve compared to the depth of what is remaining of the valve seat and feel even with a bit of machining/polishing it could not make a good seal. I think on Monday I am going to take it to Turbo Dynamics for a first opinion since they do cast iron welding etc on site. Let me know if there is anywhere else that you could recommend. For clarity these TAMD 74P's have been shoe-horned into a Princess 435 and it performs very nicely. I believe this was done by RK Marine, with no expense spared. Luckily not at my expense!! We have had the boat for over 8 years now and have the ending hours from 250 to 950 and haven't needed to top up oil or water between annual services. Only problem ever being cracked boost pressure pipe. Any more ideas regarding the turbo seat etc much appreciated.
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I remember it being done.... If it's the same boat they did a complete refurb, it took months and must have cost a fortune.

Back on topic we have 74's in our boat and other than an ecu going on the blink have been fine.
 
hector said:
I remember it being done.... If it's the same boat they did a complete refurb, it took months and must have cost a fortune.

Back on topic we have 74's in our boat and other than an ecu going on the blink have been fine.
Click to expand...

And the same pressure sensor I fitted for you that's in the ecu.
 
Thanks everyone for the replies, just an update on the progress made. The only people I could find who seemed prepared to machine the valve seat were CR Turbos. I was pleased with the result, although they kept me waiting. Although the waste gate valve looked fully extended it wasn't and the managed to free this as well. While this work was being done I removed the boost pressure switch, WD40'd it and dried it out. Put everything back together and it all seems normal. Just taken her for run out to Weymouth and all seems well. Once again, thanks for all the help. Steve
 
Hi VP I have a tamd74p-a that is bringing up code 56 sometimes and also intermittently loses power, blows black smoke on acceleration for that engine only and goes into limp mode occasionally.
Turbo is fine, waste gate is fine and no boost leaks. So i have pulled the boost sensor out of the ECU and when i look inside i can see corrosion. My question to you is can you buy them separately and if so what is the part number or where to purchase and i see there is some sort of fix to stop condensation going into the sensor can you explain what that is please and to perform.
Thanks in Advance
 
mickd said:
Hi VP I have a tamd74p-a that is bringing up code 56 sometimes and also intermittently loses power, blows black smoke on acceleration for that engine only and goes into limp mode occasionally.
Turbo is fine, waste gate is fine and no boost leaks. So i have pulled the boost sensor out of the ECU and when i look inside i can see corrosion. My question to you is can you buy them separately and if so what is the part number or where to purchase and i see there is some sort of fix to stop condensation going into the sensor can you explain what that is please and to perform.
Thanks in Advance
Click to expand...
I will look up code 5.6 sounds like an overboost issue which could be the sensor or seized wastegate .
 
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