M35A2 low power, white smoke & rough idle

[Cantrade]

I am partially through the head removal and #6 intake port is completely sooted up. The other five have clean original colors. I can't tell more right not because I can't lift the head. Shop crane will solve that problem soon.

 

[The HUlk]

I am partially through the head removal and #6 intake port is completely sooted up. The other five have clean original colors. I can't tell more right not because I can't lift the head. Shop crane will solve that problem soon.

So no air flow into #6?

 

[Cantrade]

That's the way it looks. I was seeing back flow through the air cleaner inlet at the turbo. Positive pressure there is a no-no. I suspect a blown head gasket between #5 & #6 that would let high compression gas from 5 into 6 while the intake valve was opening. I'll know more when I get the thing completely apart. I had some difficulty getting the intake and exhaust manifolds off today. Not much wrench room in there!!

 

[TB58]

sorry I didn't post up earlier, but I have an unused old style head gasket set (separate fire rings) that I won't be using.

 

[The HUlk]

That's the way it looks. I was seeing back flow through the air cleaner inlet at the turbo. Positive pressure there is a no-no. I suspect a blown head gasket between #5 & #6 that would let high compression gas from 5 into 6 while the intake valve was opening. I'll know more when I get the thing completely apart. I had some difficulty getting the intake and exhaust manifolds off today. Not much wrench room in there!!

It would seem to me that if the #6 intake port is blocked then air from the cylinder would not be moving out the intake side. That intake being blocked leads me to believe that large amounts of air is able to enter #6 from somewhere else during the intake stroke. Not drawing air in through the intake would be the only reason I could think of as to why an intake port would get blocked up unless something packed a nest in there or something.

 

[Cantrade]

The Hulk,
I don't think the #6 intake port is blocked. I think the higher pressure from an adjacent cylinder during its firing cycle is leaking into #6 while the intake valve is opening and the higher pressure forces itself out the intake and through the turbo to the air cleaner. This only happens at idle and at 1400 rpm or above there is no reverse flow of air through the air cleaner. I think the turbo gets on step and overrides the leakage pressure enough to stop the out flow from #6. However this condition would surely foul up the mixture and compression in both cylinders which would cause my loss of power. I could be totally wrong about all of this.

 

[The HUlk]

The Hulk,
I don't think the #6 intake port is blocked. I think the higher pressure from an adjacent cylinder during its firing cycle is leaking into #6 while the intake valve is opening and the higher pressure forces itself out the intake and through the turbo to the air cleaner. This only happens at idle and at 1400 rpm or above there is no reverse flow of air through the air cleaner. I think the turbo gets on step and overrides the leakage pressure enough to stop the out flow from #6. However this condition would surely foul up the mixture and compression in both cylinders which would cause my loss of power. I could be totally wrong about all of this.

Ah, sounds like you are probably correct, I thought you meant the intake was blocked. Makes sense the soot is burnt fuel from the adjacent cylinder building there because at engine speed the turbo holds it back like you mentioned. Hopefully a new gasket is all that is needed.

 

[gringeltaube]

..... I suspect a blown head gasket between #5 & #6 that would let high compression gas from 5 into 6 while the intake valve was opening....

Yes, it seems you are very close now, to finding the cause. And your analysis is making sense to me: 1) When #5 fires, #6 is on the intake stroke, with its intake valve completely open; meaning that poorly burnt fuel could escape that way and cause all that soot around the intake port. 2) When #6 fires, #5 is on exhaust stroke, so any gasses blowing from cylinder #6 into cylinder #5 would then exit through #5's exhaust valve being open.


G.

 

[Cantrade]

gringeltaube,

Exactly my reasoning. The intake of #6 looks as sooty as the exhaust but on all of the other cylinders, including #5, they look normal. The intake ports have a reddish-orange hue and, of course, the exhaust ports are sooted up. When I finally get the head off and upside down I will post a pic. Thanks for following this problem.

 

[Cantrade]

Well, I got the heads off and sure enough it was as we expected. Broken and open gasket between #5 & #6 cylinders. I have enclosed three photos taken prior to clean up and inspection. The one of the ports shows how the reverse gas flow happened at low engine speeds. This has been an interesting problem and I have learned tons about the way these diesel engines are built and perform. Thanks for all of the valuable input from you guys. I appreciate it.

 

[gringeltaube]

WOW, I have never seen a MF-head-gasket burnt up that bad!
Great pics, and we can all learn from it.

Now to check the head(s ) for straightness...!


G.

 

[donnerwetter58]

Well, I got the heads off and sure enough it was as we expected. Broken and open gasket between #5 & #6 cylinders. I have enclosed three photos taken prior to clean up and inspection. The one of the ports shows how the reverse gas flow happened at low engine speeds. This has been an interesting problem and I have learned tons about the way these diesel engines are built and perform. Thanks for all of the valuable input from you guys. I appreciate it.


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From my years as an auto mechanic, a compression test is one of the first things done when diagnosing less than obvious engine problems. It would have saved much effort in this case.
Glad you eventually found the problem.

 

[The King Machine]

Well, I got the heads off and sure enough it was as we expected. Broken and open gasket between #5 & #6 cylinders. I have enclosed three photos taken prior to clean up and inspection. The one of the ports shows how the reverse gas flow happened at low engine speeds. This has been an interesting problem and I have learned tons about the way these diesel engines are built and perform. Thanks for all of the valuable input from you guys. I appreciate it.


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When I pulled my heads off I had a similar issue. Although not as bad, mine was on its way there. What happened to the bits of metal fire ring that broke loose?

 

[Cantrade]

Donnerwetter58: Absolutely. The problem is that this is my very first attempt to troubleshoot a diesel problem and none of my three compression gauges fit the FI ports and are even of the proper range. It is a 100 mile round trip to the nearest town of any size which eats up time and fuel. I plan to find the correct compression gauge and buy one soon. I have a great injector test set up now but still need a few more diagnostic tools to do the job right. On the bright side, I have been on a straight up learning curve which is priceless.

 

[Cantrade]

No idea, but I hope they burned up slowly or went out the exhaust. The cylinders look great and aren't scored.

 

[rustystud]

Donnerwetter58: Absolutely. The problem is that this is my very first attempt to troubleshoot a diesel problem and none of my three compression gauges fit the FI ports and are even of the proper range. It is a 100 mile round trip to the nearest town of any size which eats up time and fuel. I plan to find the correct compression gauge and buy one soon. I have a great injector test set up now but still need a few more diagnostic tools to do the job right. On the bright side, I have been on a straight up learning curve which is priceless.

You can order the compression adapter for the Hercules engines from any White tractor supplier. I bought one just last year for about $80.00 . I cannot remember the model of tractor that uses the same engine as our multifuels but I know JasonS knows ! I think it is something along the lines of a 5-155 ? or maybe it's a 2-155 tractor ? My brain is mush tonight.

 

[rustystud]

Well, I got the heads off and sure enough it was as we expected. Broken and open gasket between #5 & #6 cylinders. I have enclosed three photos taken prior to clean up and inspection. The one of the ports shows how the reverse gas flow happened at low engine speeds. This has been an interesting problem and I have learned tons about the way these diesel engines are built and perform. Thanks for all of the valuable input from you guys. I appreciate it.


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Well at least you didn't burn the head ! I have seen burn marks on heads that looked like someone used a torch on it. Your's look like a simple resurfacing will clean them right up.

 

[tommys2patrick]

Cantrade--very good job! Great photos and diagnosing the problem followed a good thought process. Good to have all the great folks on the forum sharing there thoughts as well. While I don't have this problem with my MV ( at the moment anyway), I will definitely store your shared experience for future reference. Thanks.

 

[RaggedyMan]

Is there something specific that causes these gaskets to fail often and/or is it something that can be prevented to some extent? (I'm a gas engine guy so maybe it's a diesel thing) Seems like I see or have seen a lot of posts about failed head gaskets, could be only because people never post about how well or long their head gaskets last I suppose. Are there any MF's out there with head gasket that have lasted "forever"?

 

[Cantrade]

Rustystud: Thanks for the information. I will look around and order a compression gauge. I had no idea that these engines were used in tractors also. BTW, I put a straight edge on both heads after cleaning off the gasket and other junk and found that they are flat everywhere except between the cylinders where there is about a .002" - .003" clearance. That narrow section is where the gasket blew. It's off to the machine shop for a resurfacing job on both heads.

tommys2patrick: Thanks for the comments. I was hesitant about exposing my lack of knowledge and experience with these engines but decided that I needed all the help I could get. This is the place to do that.

RaggedyMan: I don't know about the longevity of the past head gaskets but I ordered a complete head gasket set from Memphis Equip. and the parts person said that they now only sell the "upgraded" ones that have the fire ring built into the gasket and not a separate piece as in the past. Maybe with this new design, slight milling of the head, plus a careful torque job this repair will last awhile. I have owned 4 Cummins engines in pick ups and have never had any problems other than a cracked exhaust manifold.