Installed rebuilt turbo, now engine temp up 5-10 degrees

[Seawayva]

I had the turbo rebuilt on my Yanmar 4lha Stp and I just finished reinstalling it this morning. Everything seemed to be fine, turbo spooled up as it should, boat reached its normal speeds, but the temperature climbed to just under 180 under load. Normally it runs at a bit under 170 at load. Idle temp is 160 as it has always been. When I took the load off the engine, it quickly returned to 160.

Some coolant was lost when reinstalling the lines to the turbo, but the amount was under 12 ounces, oil pressure seems to be good, the temp just seemed high. The water temperature on the river is about 80.

Any thoughts? Clean the heat exchanger? New coolant? Impeller?

There also is not a bleed valve at the turbo to remove air introduced to the system, is this normal? Will the air in the cooling system purge itself?

Thanks for any and all help.

 

[djmarchand]

I can think of a couple of reasons why your engine temp has gone up:

The simplest is that it was happening anyway and now that seawater temps are at their max it now is evident.

The other reason depends on why you rebuilt your turbo. If you had been operating it for all of this summer with low boost, then it was producing less power and the (degraded) cooling system could keep up. Now that it is producing full power, the cooling system can't keep up. Somewhat similar to the first theory.

The solution of course is to clean all heat exchangers, not just the seawater to coolant exchanger but all including the air cooler. If your air cooler is fouled, air side or water side, it will allow much hotter air into the engine, which in addition to adding more load to the coolant system, could melt a piston.

David

 

[Seawayva]

I can think of a couple of reasons why your engine temp has gone up:

The simplest is that it was happening anyway and now that seawater temps are at their max it now is evident.

The other reason depends on why you rebuilt your turbo. If you had been operating it for all of this summer with low boost, then it was producing less power and the (degraded) cooling system could keep up. Now that it is producing full power, the cooling system can't keep up. Somewhat similar to the first theory.

The solution of course is to clean all heat exchangers, not just the seawater to coolant exchanger but all including the air cooler. If your air cooler is fouled, air side or water side, it will allow much hotter air into the engine, which in addition to adding more load to the coolant system, could melt a piston.

David

Thanks for the reply, David. The turbo was rebuilt because it wasn't producing any boost. Turned out to be a stuck waste gate and gummed up waste gate actuator.

I will address the all the cooling system next.

 

[plowin]

Its very possible its running exactly where it should now that the turbo is working correctly.

 

[Seawayva]

Its very possible its running exactly where it should now that the turbo is working correctly.

180 doesn't seem too hot?

 

[plowin]

Depends or what the thermostats are but generally speaking 180 under load is just fine. Additionally a properly operating turbo is going to produce much more power than one producing no boost, that equals heat(bigger bang plus more combustion) as long as the temp stays within the thermostats range your good.

 

[captainlarry84]

Tempertures

I can think of a couple of reasons why your engine temp has gone up:

The simplest is that it was happening anyway and now that seawater temps are at their max it now is evident.

The other reason depends on why you rebuilt your turbo. If you had been operating it for all of this summer with low boost, then it was producing less power and the (degraded) cooling system could keep up. Now that it is producing full power, the cooling system can't keep up. Somewhat similar to the first theory.

The solution of course is to clean all heat exchangers, not just the seawater to coolant exchanger but all including the air cooler. If your air cooler is fouled, air side or water side, it will allow much hotter air into the engine, which in addition to adding more load to the coolant system, could melt a piston.


David

A good post, Dave hit on all good points. If your Yanmars has over 1500 hours it is most likely time to clean the heat exchangers. The increase temps could be from the increase power performance. But the exchanger can really creep up on you. On your Yanmar if the temps clime when running from 3000 RPMs to WOT then it is most likely the exchanger. Yanmars have great cooling systems and even under full load the temp should lock in and stay in. The attached photo shows my Yanmar panel at WOT for over two minute. The gauge locks in at that spot and stays there. As should yours. The Reydlime process is a snap to clean your heating system with no dismantling.

The two photos should my Yanmar Panel #1 at WOT 3500 RPMs & #2 at 3000 RPMs note that in both photos the temp gauge is dead center of the meter.

 

[Seawayva]

Captain Larry, what is the process to clean the heat exchanger using Rydlyme?

 

[peterl]

Had the same scenario. Installed a NEW factory turbo.. Temp went up 15 degrees.. Cleaned out the Heat Exchange, etc.. turned out being the sending unit.. Replaced and temp went back down..

 

[Seawayva]

Had the same scenario. Installed a NEW factory turbo.. Temp went up 15 degrees.. Cleaned out the Heat Exchange, etc.. turned out being the sending unit.. Replaced and temp went back down..

Forgive my ignorance, but does was the sending unit simply reporting the wrong temperature?

 

[peterl]

Strangely! but yes.. probed with a laser heat gun before and beyond the sending unit revealing a lower temp than the gauge..

 

[Seawayva]

Strangely! but yes.. probed with a laser heat gun before and beyond the sending unit revealing a lower temp than the gauge..

I guess I will have look into that as well! Is your engine a yanmar as well? If so what temperature do you normally run under load?

 

[peterl]

(2001) CAT 3126, 300 hp. 180-185 degrees..

 

[Seawayva]

(2001) CAT 3126, 300 hp. 180-185 degrees..

Makes me wonder if I am okay at 180. I can assure you of one thing, I am learning a lot about diesels with this exercise. I also drive a 1987 Mercedes diesel and the thing is bullet proof. Add water and the complexity is ten fold. I really appreciate your help.

Matt

 

[peterl]

I would still check with a laser gun. Also look into the correct temp for your engine.. Help is my pleasure!! Anytime Matt.. Pete

 

[delucat2]

A new properly functioning turbo will reveal all the faults your engine was building up over the past few years. The heat x, aftercooler, and oil cooler are all building up scale and salt over time. The raw water pump is getting old and pushing less water. You had turbo issues - most likely taking salt water up the exhaust and into the turbo, right down and into the wastegate. Boost has fallen off, resulting in lower temps and more black smoke. You now slap on a new turbo, produce full boost and burn all fuel, so yes, you will see higher temps as the cooling system is aging.

The most important question to answer is this... did you figure out why the turbo failed. If no, you are probably going to go down the same path of destruction with this one. These turbos should last 15,000+ hours if taken care of. Something is very wrong.

TonyD

 

[Seawayva]

A new properly functioning turbo will reveal all the faults your engine was building up over the past few years. The heat x, aftercooler, and oil cooler are all building up scale and salt over time. The raw water pump is getting old and pushing less water. You had turbo issues - most likely taking salt water up the exhaust and into the turbo, right down and into the wastegate. Boost has fallen off, resulting in lower temps and more black smoke. You now slap on a new turbo, produce full boost and burn all fuel, so yes, you will see higher temps as the cooling system is aging.

The most important question to answer is this... did you figure out why the turbo failed. If no, you are probably going to go down the same path of destruction with this one. These turbos should last 15,000+ hours if taken care of. Something is very wrong.

TonyD

Well the boat has been run exclusively in fresh water for the past 4 years, so I am pretty sure that salt intrusion isn't the issue. The turbo was not corroded on the exhaust side, so water intrusion seems an unlikely cause. What I believe happened is I simply didn't run the boat hard enough. A bunch of short trips at low RPM without getting the engine up to temp and then not running the boat at high RPM to burn off the excess carbon as is recommended. This caused carbon build up at the waste gate not allowing it to fully close, according to the guy who did the rebuild. He must have been on the right track as now the turbo spools up as it should.

I am interested to know how many rebuilds are anticipated in the 15,000 hour lifespan of these turbos.

My other question is that the service manual states that the thermostat is 85 degrees celsius or 185 degrees F. If I am now running, at say 2900 or about 10% off max RPM at 180 degrees, is this cause for alarm? Before the rebuild I was running closer to 170 degrees F. My desire is to assess the problem and fix it and to mitigate problems down the line. Your assessment that "Something is very wrong" is what has me puzzled. Admittedly I don't know a thing about this, but I am certainly trying to learn which is why I am here asking questions and trying to ascertain what the next good step to making certain that the problem I had previously doesn't reappear and that the rebuilt turbo hasn't ucovered some other issues that it's degraded performance was hiding, namely the cooling system.

 

[plowin]

As I was hoping, for your sake, you have not even reached your max operating temperature yet. Double check the temperature if you like and run it. If the temperature goes over 185 then you have reason to be concerned. I think that sometimes we overthink this stuff, let the engine do what it was meant to do. Not to say that being concerned about changes in engine operation are being over thought, its just when you are within four specs and things seem to change a bit due to an upgrade or improvement I think we should let the engine "see what she can do" you might be surprised.

 

[Seawayva]

As I was hoping, for your sake, you have not even reached your max operating temperature yet. Double check the temperature if you like and run it. If the temperature goes over 185 then you have reason to be concerned. I think that sometimes we overthink this stuff, let the engine do what it was meant to do. Not to say that being concerned about changes in engine operation are being over thought, its just when you are within four specs and things seem to change a bit due to an upgrade or improvement I think we should let the engine "see what she can do" you might be surprised.

I am certain I am overthinking it. I am just not that well versed in all of this and that leads to confusion. The other problem is the vast amount in info available as well as the varying opinions that the internet provides. TonyD seems to think I am bound for failure while others seem to think I am well within the limits of the engine. I want it to be right so I can use the boat and have fun as opposed to using the boat and constantly being concerned that I am on the brink of total failure. Experience breeds confidence, since I am short on the experience, I am leary.

The boat seemed to run well yesterday. Sounded good, was quiet, pumped water like it should, the engine responded like it should and it got to speed and max RPM without trouble.

Thanks for your thoughts!

 

[jojobee]

185 degrees is the spec for this engine.

Call me if you have questions.
joe 908-337-4789