D4H under load blows light grey smoke

[CatToy]

After all the rain the past few weeks in SE Tn., I finally had a chance to run my new to me D4H for about an hour. After some light pushing of a few small piles of dirt, headed to my pond to push around some piles of silt I need to spread out. Starting noticing light grey smoke coming from the front of the dozer radiator when I put a real heavy load on it. Thought I had an oil leak but as soon as I put it in neutral it started clearing up. No smoke at max throttle, moving around not under load or light load. The best I can tell, the smoke smells like normal diesel exhaust (hard to stop and juup off the dozer and run out in front of it and catch up to the smoke when the wind is blowing, my wife thought I was going crazy or getting chased by yellowjackets). The dozer had sat for several months before I bought it, so I drained the fuel, changed all the filters and fluids, it starts great and runs great as far as I can tell. So, what do I need to look at?

Second question, based on the soot on the motor and the above issue, and not being able to find an exhaust leak, it seems the fan is pulling exhaust fumes back into the engine compartment from the gap where the muffler and hood/stack meet. I can stick my fingers in the gap, so that is about the size all the way around. What can I do to stop exhaust from getting pulled back thru the fan?

Some info to help, it is SN9DB01218, unknown hours with a 3204 engine.

 

[Nige]

OK, so it's blowing grey smoke out of the radiator - obviously sucked from the engine compartment - how much and what colour of smoke is getting blown out of the chimney..?

As I see it your most likely cause is an exhaust leak somewhere under the hood, not sucking smoke through the gap between the muffler and hood.
Just to confirm. Does the fan on your tractor blow hot air forwards out of the radiator..? That's pretty much normal altough some tractors are equipped with fans that suck rather than blow so we need to ascertain what type yours has right from the get-go.

As a suggestion have someone hold a rag over the top of the exhaust stack and then start the engine from cold with the side doors open. See if you can spot black smoke coming out from anywhere it shouldn't. At startup you're going to get loads of unburnt fuel therefore the smoke will be thicker and theoretically easier to spot where it's coming from.
IIRC 3204's were famous for failing exhaust manifold gaskets.

 

[CatToy]

Fan blows air out the front, it puts out a good cloud of smoke and it is white grey. I first thought it was burning oil but it did not smell like oil or antifreeze. I covered the exhaust, it leaks where the turbo exhaust pipe goes into the muffler. After removing the exhaust guard, you can see the soot under the hood and on the muffler. I felt around the exhaust manifold the best I could before it became too hot and did not feel any leaks.

 

[kshansen]

Looks like you found the problem!

Actually looks like that pipe is not in the muffler very far. Maybe something was not lined up right when assembled last. Here is a picture out of parts book on SIS:


See how close the shoulder is to the muffler in the drawing? Yours looks to have over an inch between the muffler and the shoulder on the pipe to the turbo.

 

[Nige]

It's likely that the spring-steel ring (Item #2) that seals the pipe from the turbo has seized into the groove in the tube. You'll need 1 x 6N-0992 Ring and if the clamp at the other end is buggered order 1 x 3H-8604, 2 x 5M-2894, 1 x 1D-4717, & 1 x 0S-1571 (Items #3, 4, 5, & 6). The 5 Part Numbers are only about $15 in total. The only fly in the oitment will be if you find a crack the end of the tube where the groove for the ring is located. A replacement tube is $110 and might be cheaper than trying to fix the old one.

You'll probably have to break the old ring into pieces to remove it from the groove because it will be seized in there tight with carbon. Before installing the new ring make sure that the groove is wide enough that the ring will spin freely. Also polish the inside of the muffler with a flap wheel before installing the tube. If you have to drive the new ring into the groove the groove ain't wide enough. Don't put any exhaust putty or anything else on the ring when it's installed, the exhaust gas will seal it given a few hours of operation.

 

[CatToy]

Thanks for the picture. I looked at it again based on the drawing, I do not see any way to adjust or seat it deeper unless something is bent where it mounts. But your parts show a seal ring which I do not see or feel, so I think it is missing (based on the soot, has been for a while).

Thanks for the drawings and tips. BTW- how do I get access to the drawings like you guys have?

 

[Nige]

I would say most likely the black ring on the pipe is from soot blowing out of the joint. I think you need to pull the exhaust pipe out of the muffler and see how deep it is seated. I'm not sure that is the issue, I am reasonably sure that you will find the ring seized and the pipe somewhat loose in the muffler.

Also another thought came to me. when you pull it apart check to see if the ring has gouged a groove in the muffler (the ring is harder than the muffler. Simply replacing the ring under those circumstances will not cure the leak unless you can fill the groove in the muffler with welding or brazing and grind it smooth in order to present a smooth surface for the ring to seal on.

 

[CatToy]

I would say most likely the black ring is from soot blowing out of the joint. I think you need to pull the exhaust pipe out of the muffler and see how deep it is seated. I'm not sure that is the issue, I am reasonably sure that you will find the ring seized and the pipe somewhat loose in the muffler.

Also another though came to me. It may be that the ring has gouged a groove in the muffler (the ring is harder than the muffler. Simply replacing the ring under those circumstances will not cure the leak unless you can fill the groove in the muffler with welding or brazing and grind it smooth.

Hmm, gouged pipe does not sound like good thing, I was planning on pulling the hood to have better access, that will make it easier if I need to pull the muffler. Do they set it up this way for vibration concerns? Seems overly complicated.

 

[Nige]

The groove in the muffler is only a possibility. I have seen it before, just not very often. I wanted to make sure you were aware of it so that you could check for wear in the intake pipe of the muffler while you had everything apart and take appropriate action if necessary.

If it was me I'd simply pull out the pipe checking for any wear in the tube into the muffler at that time, clean it all up then replace the ring at one end and the clamp & hardware at the other and fire the whole shooting match back together.

 

[Mjrdude1]

Cat used this setup for a very long time, and still does on some applications. Not so much for vibration as it is for growth of the hot exhaust parts as they heat up, and ease of assembly. Easiest way to gain access will be to remove the muffler mounting bolts, then you can slide the muffler away from the pipe. As the others have said, most likely the ring is rusted or carbon seized in the groove.
Take a peek at the radiator while you are there, seen the solder come loose from too much exhaust heat at times.

 

[Queenslander]

how do I get access to the drawings like you guys have?

Sign up to Partstore through your Cat dealer.
You can do it online, at no cost, but you may have to open a trading account.
Allows access to those drawings, pricing, availability and you can order parts 24/7.

 

[Oxbow]

Sign up to Partstore through your Cat dealer.
You can do it online, at no cost, but you may have to open a trading account.
Allows access to those drawings, pricing, availability and you can order parts 24/7.

I thought it required an annual subscription fee of $700 or so U.S.?

I would like to have the access as well, but my needs do not warrant the fee.

 

[Queenslander]

Definitely no charges with our dealer, in fact, they are constantly encouraging customers to use it.
Takes some load off the parts people on the phones I guess.

 

[Cmark]

Access to parts listings is generally free but all the other areas of SIS; schematics, D&A, sys-op etc. have to be paid for.

 

[Queenslander]

Possibly, if they allowed further free access to some areas of sis, schematics for example, it might take even more pressure off support staff,
I have a customer support rep. that I annoy constantly.

 

[CatToy]

Yep, just stopped by my local dealer to pick up parts for my muffler repair and signed up for parts access for free but everything else is only available for fleet owners or thru the service staff. That is fine with me, they are only 4 miles away, plus all you guys seem to not mind folks asking what must be to you really dumb questions.

I guess I need to break down and buy the shop manual, I see more work in my future.

 

[Mjrdude1]

Just re-read your OP, and the gap is intentional between the muffler and stack, serves a couple functions, one is to act as a venturi and pull air from the compartment so the stack itself doesn't get as hot, and also to keep rain water from getting into the muffler and possibly engine. The water sticks on the pipe walls and drips off. Just a tad more info for ya.

 

[CatToy]

Actually looks like that pipe is not in the muffler very far. Maybe something was not lined up right when assembled last. Yours looks to have over an inch between the muffler and the shoulder on the pipe to the turbo.

Well, you are correct, I removed the bolts for the muffler and slide it back, the pipe is only about 1" into the muffler. There is a lip about 2-3" inside the muffler that looks like the pipe should seat up against, question for the experts, should it? I checked over the mounting of the turbo and muffler but I do not see any way to adjust.

Next, I have 2 seal rings that came in the package, I was only expecting one, do I use both and how do they fit on the pipe? I have what looks like what used to be a two lips (one mostly gone) around the pipe with a 1/8" gap between or maybe that t is where two seal rings welded themselves to the pipe. If these are the old rings, they are not coming off the pipe. I will take some pictures tomorrow, it started raining as I was working so I quit before I could take pictures.

 

[Nige]

Well, you are correct, I removed the bolts for the muffler and slide it back, the pipe is only about 1" into the muffler. There is a lip about 2-3" inside the muffler that looks like the pipe should seat up against, question for the experts, should it? I checked over the mounting of the turbo and muffler but I do not see any way to adjust.

Next, I have 2 seal rings that came in the package, I was only expecting one, do I use both and how do they fit on the pipe? I have what looks like what used to be a two lips (one mostly gone) around the pipe with a 1/8" gap between or maybe that t is where two seal rings welded themselves to the pipe. If these are the old rings, they are not coming off the pipe. I will take some pictures tomorrow, it started raining as I was working so I quit before I could take pictures.

In answer to your first question the pipe should not be all the way into the muffler. That is to take care of expansion. If there is a 3" lip on the muffler I would have expected the exhaust pipe to go in about half way or thereabouts so yours is not far away, if possibly a tad short. I'd suggest reinstalling the pipe minus ring and clamp and play around with moving it a hair back and forth where the clamp #6 fits to see if you can get it deeper into the muffler without the alignment going out of whack. Also try loosening the holding down boits for the muffler and see if it will move to the left a tad. If not then that's where it's supposed to go.

Regarding your second question. If you go back to the diagram posted earlier you will actually find that there are 2 of the rings (Item #2) in the whole assembly as shown in the diagram, the other one is at the bottom left where the elbow comes out of the turbo. However to reseal your exhaust leak you only require one of them so take the 2nd one back. You don't need it. The two "rings" that you can see on the end of the pipe are actually part of the pipe and the loose ring fits in between them. It sounds as though the spring-steel ring was missing completely on your tractor. Post some good photos of the end of the pipe where you say one of the lips is almost gone. That could be bad news although if the exhaust gas leak was as small as you say it was with no ring in there at all then maybe simply installing the ring will cure the problem. You can but try.

 

[CatToy]

Got a break in the rain this afternoon, installed the ring and reassembled. Stopped about 90% but still leaks a little around the top because it is not perfectly centered in the muffler, it is a hair low. The pipe was rusted to the turbo exhaust pipe, I was afraid I would damage both if I worked any harder to get it free I think. I will need to replace the pipe to do any better.

Also attached a picture of the exhaust that I was seeing but it was about twice as heavy before, I was not able to really load it in the mud today.