6v92 Exhaust Clamp Leak(s)

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6v92 Exhaust Clamp Leak(s)

July 25, 2016, 03:06:35 pm

I've been noticing for some time that my exhaust has become blacker on the climbs. Worried that my 190,000 mile engine might be hitting end of life I started googling "6v92 black smoke". Found that this usually means you have an exhaust leak and the turbo is not putting enough air in the engine to burn all of the fuel resulting in black smoke. Had Dori start the engine (while cold) while I stood at the engine compartment. Sure enough I could see exhaust escaping from all 4 exhaust clamps!

I loosened all clamps and rotated 90Âº or so to reseat and tighten the crap out of them. Drove to the next campground and was still seeing black smoke. Checked the clamps and they were loose again. I assume from the expansion and contraction. Tightened the crap out of them again but still had black smoke going to the next campground. Checked clamps again and they were tight so determined that was not the issue. Had Dori do the cold start while I watched and all 4 clamps are still leaking.

Decided this project was going to take a little more work than some wrench turning. Pulled one of the exhaust pipes and sure enough there is soot everywhere. I'm going to clean everything up the best I can and thinking about replacing the exhaust clamps. Not sure I need to do that as the clamps look ok just dirty/sooty. Plan is to clean up the flanges the best I can with a scotch brite. I can pull the turbo inlet to make it a little easier to work on but don't plan to pull the exhaust manifolds. A little worried about getting debris in the system. Pretty sure the turbo wouldn't like that. One of the flanges does have a small dent in it will try to reshape that.

It doesn't look like there's a gasket used just the pressure fit from the clamps to seal the exhaust. I did find a "Hi-TempJointing Compound" called Silkolene. It's highly recommended but at over $100 for 8oz I'm not too crazy about buying it. I did find another "Jointing compound" but not sure it's suitable for the temperatures the exhaust will see. It's Walker 35959 Hardware Sealing Compound. Anyone every use this. Looks like it's more for slip joint muffler pipe. I like the price a whole lot better.

I'm sure the exhaust side of the turbo looks as sooty as the exhaust pipe. Will that adversely performance of the turbo to any great degree? Can it be cleaned or am I looking at a new turbo somewhere down the road?

Any advise or opinions welcome especially from fellow 6v92 owners.

see ya
ken

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Re: 6v92 Exhaust Clamp Leak(s)

Reply #1 – July 25, 2016, 03:41:43 pm

We've blown a couple of turbos, and the color is grey/white, so you might be on to something about the connections. The lag seems to be, that, depending on the engine,/turbo, it's a different color smoke if a turbo goes south. Are you burning oil, big time? Hope Dori is doing well. There is a fixer-upper for sale down here, should you (or me, with an oil leak I can't find), could be a good choice.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #2 – July 25, 2016, 04:15:14 pm

Leaks downstream of the turbo doesn't cause a rich fuel mixture, just soot. Exhaust leaks at the manifold reduce boost pressure. Usually the connections carbon up and seal with the type in your pics.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #3 – July 25, 2016, 04:25:40 pm

Quote from: craneman – July 25, 2016, 04:15:14 pm

Leaks downstream of the turbo doesn't cause a rich fuel mixture, just soot. Exhaust leaks at the manifold reduce boost pressure. Usually the connections carbon up and seal with the type in your pics.

~~Definitely upstream of the turbo.~~ Have to take that back. I've been so focused on the exhaust leaks haven't checked the downstream side.

see ya
ken

Re: 6v92 Exhaust Clamp Leak(s)

Reply #4 – July 25, 2016, 04:38:48 pm

Ken.

Looks like a good cleaning on the mating surfaces of the pipes and clamps is in order. Your clamps may be sprung beyond where the tapered part is effective but before replacing them clean the inner mating surface good along with the clamping bolt. Get some C-5A Felpro (here is what you are looking for) C5-A® Copper Based Anti-Seize Compound technical info c5a loctite fel-pro felpro (no this isn't my company so shop around for the best $) Use this on the mating surfaces of the exhaust pipe along with the clamp tapered surfaces Make sure you put some on the clamp bolt threads as this will help with tightening. Now put everything back together. Once clamps are good and snug give them a LIGHT tap (think small hammer you don't want to break your turbo casting) all around to help them tighten up. Re tighten clamp bolts. Crank up and heat up system. Re tighten clamp bolts. If this fails then I would look for some new exhaust clamps.

With the black exhaust you describe I would be looking for a leak on the other side of the turbo as you may be loosing air on that side. Check your waste gate to see if it is sticking. You haven't even come close to using up that engine you just need to find what seems to be a little air leak. (craneman beat me to this line of reasoning while I was typing)

Pamela & Mike

Re: 6v92 Exhaust Clamp Leak(s)

Reply #5 – July 25, 2016, 04:58:53 pm

All else being equal, I would take a long hard look at the waste gate and the control hoses to it.
you are losing "boost"(read manifold) pressure, either at the turbo & hoses/tubing to the engine (not the exhaust side) or at the waste gate.
If all else fails a stop @ a Detroit dealer may be in order to find out whats what.
You may find that all that is needed is a clamp or three or the overhead "rack" needs to be run...
Or the bad would be that the pump is in need of rebuild, the 2 strokes really really do not like the ultra low sulfur diesel.

Just remember that Detroits are like Harleys... when they quit leaking oil.... they are out of oil!

Re: 6v92 Exhaust Clamp Leak(s)

Reply #6 – July 25, 2016, 06:46:18 pm

The turbo feeds directly into the blower on top of the engine. Ken I think you might have a leaky or dirty injector. Do you use any fuel treatment?
If not Add some Power Service fuel injector cleaner it's in a grey bottle.
At 190k if the injectors are original you are in their lifespan ballpark.
I wouldn't bother doing a bunch of cleaning on the exhaust pipe unless you just really want to get black and dirty.Replace all the joint clamps but I think you'regoing to find the cause in the fuel supply myself,with dirty injectors, worn injectors,or possibly a overhead needing adjustment.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #7 – July 28, 2016, 06:48:21 am

I has been a really long time since I last worked on a 6V92 and I have tried really hard to forget everything that I ever knew about 2 stroke detroits (not a fan, too many long nights in the field wrenching on the things)

If you are having lots of smoke on acceleration and a bit doggy on the throttle response, it could be a partially plugged after-cooler.

Just trying to remember everything here.

On a T/A Detroit 2 stroke, the aftercooler is under the blower in the valley.
Not a fun thing to get at.
If the turbo(s) or blower are passing any oil at all, it will have a tendency to plug up the cooler.
The hot air coming from the turbo will have tendency to bake the oil and turn it into a kind of black sludge
Any soot or dirt that manages to get past the air cleaner will cause some blockage also.

You can google it,

Depending on how bad your smoke problem is, (light smoke I would not ever bother with it) a cleaning will do wonders.

I have never pulled on on a 6-92, most of my experience is on the good old buzzing dozen (12V71's) in industrial settings. I have seen them plugged so bad you wouldn't think the engine could run. Run they did but heavy heavy smoke on acceleration and horrible fuel economy (not that those things got any kind of economy).

I threw all of my detroit books out years ago, so I can't even look anything up anymore (told you I was trying hard to forget them), gave all of my tune up tooling away. Oh man, it must be 25 years since I last did one of these.

So I'm really not the best person to ask about detroits anymore, just something about smoking rang a bell.

And looking at the pictures you have, it looks to me like the flanges on the pipes are finished, manifolds look okay, but the flanges don't look good, Pic 4582 looks really bad and 4573, good luck trying to get that back.
If you do use some kind of compound to try to seal, use very sparingly, anything that goes to the inside of the pipe can break off and damage your turbo, so no muffler cement please

The old detroits smoke and soot, your exhaust will be full of soot. No big deal. If a new set of clamps does not help, your pretty much looking at a set of pipes.

Hate to be a Krampus here,

Feel free to PM me, I can try to unlock the old brain, but there are some things that you just want to forget.
It might take me a few days to get back to you if you do PM, pretty busy right now.

My latest engine I have to learn about is the DD16 liter. These things are crazy.

Brian

Re: 6v92 Exhaust Clamp Leak(s)

Reply #8 – July 28, 2016, 03:36:44 pm

Thanks Brain! I have clamps ordered. They should be here tomorrow. Will clean up the flanges and use the anti-seize that Mike suggested. If that doesn't work will be visiting Stewart and Stevenson in Denver when we are there in a couple of weeks.

see ya
ken

Re: 6v92 Exhaust Clamp Leak(s)

Reply #9 – July 28, 2016, 03:46:12 pm

Ken,

Might be slight overkill, but were it me, while they are off/loose, I would use some valve lapping compound on the mating surfaces to clean them up and insure a closer fit.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #10 – July 28, 2016, 04:06:52 pm

Quote from: wolfe10 – July 28, 2016, 03:46:12 pm

Might be slight overkill, but were it me, while they are off/loose, I would use some valve lapping compound on the mating surfaces to clean them up and insure a closer fit.

There is no overkill at Ken's stage, he's prolly running low on storage for "nerve medicine" by now. I'd be curious if there is a way to test the turbo without removing it? If the injectors are original, could be where I'd go, given the age & color of the smoke.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #11 – July 28, 2016, 07:04:11 pm

Here is a bit more information the the exhaust clamps and such

http://india.donaldson.com/en/exhaust/support/datalibrary/061237.pdf

Donaldson exhaust catalog.

Look at pages 21 and 22, there are some size so you have some reference to work with.

I believe those pipes are in the 3 to 3.5 inch range. Don't worry about what they are, just use the information for measuring.
On page 22, the little diagram right by the accessory tab shows the flange.
they don't have a 6V92 listed ,but I do believe that it is the 3", so if you look at dimension B and C, this is what you are looking for.
You are basically dealing with about 1/2" of flange the the clamp is going to squeeze to the manifold. If you don't have that dimension it is just about impossible to get a good seal.
The last picture in your series looks like that flange is pretty much done.

The pipes from exhaust manifold to turbo used to be pretty easy to find and that would be the best fix.
The trouble is, as the old green leakers have become obsolete, parts get harder and harder to find until the offshore ones come on line.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #12 – July 29, 2016, 12:15:09 am

Just gonna throw this out there... dirty air filter so not getting enough air to begin with? OR.... rubber hose/tube @ elbow has split on the inside and the "flap" is plugging up the works?? I have seen both

Re: 6v92 Exhaust Clamp Leak(s)

Reply #13 – August 03, 2016, 12:43:08 pm

Got my clamps but they are one size too big.

Cleaned up my existing clamps and found one had cracks in it. Put everything back together and changed campgrounds from Gunnison to Buena Vista going over Monarch Pass eastbound. Made it over no problem just trailing more black smoke than I'd like. Noticed on the VMSpc that my boost never made it past 10psi. Usually runs up to 19psi.

Cleaned my exhaust pipes and fittings. A couple showed some severe pitting. May be looking for new ones.

Made it over the pass without any heating problems. My dash gauge showed over 200º most of the way but the VMSpc never made it over 190º. Maybe need to check the ground wire on that dash gauge or do a r&r. Think maybe without the usual boost the horsepower was down which kept the heat down. I was only going 25mph in steep sections. I was towing my Xterra. (4500lbs)

Booking an appointment with Stewart & Stevenson in Denver. Will be a couple of weeks before we get there.

see ya
ken

Re: 6v92 Exhaust Clamp Leak(s)

Reply #14 – August 03, 2016, 12:55:47 pm

Quote from: saddlesore – July 29, 2016, 12:15:09 am

Just gonna throw this out there... dirty air filter so not getting enough air to begin with? OR.... rubber hose/tube @ elbow has split on the inside and the "flap" is plugging up the works?? I have seen both

Air filter is only a couple months old and the indicator barely shows any restriction.

I just checked the big rubber elbow off the back of the filter and it looks in great shape.

Thanks for the suggestions.

see ya
ken

Re: 6v92 Exhaust Clamp Leak(s)

Reply #15 – August 03, 2016, 01:14:03 pm

Well, at least you're cooking down the road! We drove back to WA one time with a blown turbo and it was not pretty.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #16 – August 03, 2016, 04:25:11 pm

Quote from: kenhat – August 03, 2016, 12:43:08 pm

Noticed on the VMSpc that my boost never made it past 10psi. Usually runs up to 19psi.

That boost is way low. I see about 21 psi at 2500 ft elevation. Maybe 19 psi is normal for your elevations in Colorado.
I would get the pipe leaks fixed and also consider getting the turbo rebuilt. Here's an old thread on the subject: Turbo problems?

I took my turbo off and had a diesel injector shop rebuild it. It was about $450 with me pulling it and re-installing it. The exhaust connections was a real pain to get off; cycles of applying heat and diesel on the joint and hammering with a chisel at the joint. It took a couple days effort working on and off - seemed like I was going no where for a long time and then it started moving. I did mine at 140k miles due to a periodic bearing type buzz noise I heard while driving. Was pleasantly surprised with the new giddy up that came as a bonus. I didn't have the VMS back then so I don't know the before boost psi.

Here's the DD "Turbo Technician's Guide": http://www.foreforums.com/index.php?action=media;sa=item;in=2251
While you would have to remove the exhaust connection to see the hot side, the cool intake side is easy to view by pulling the boot.
Turbo boost psi and the guide should help you decide if yours is "ready".

Re: 6v92 Exhaust Clamp Leak(s)

Reply #17 – August 04, 2016, 08:00:19 am

I have never seen boost numbers greater than 19 psi on my 93 engine. In fact I had the top end redone, heads milled new gaskets etc, this spring and the boost numbers seldom reach 19. Bernd the diesel mechanic in NAC tells me 19 is typical for the 6V92/

Re: 6v92 Exhaust Clamp Leak(s)

Reply #18 – August 04, 2016, 09:40:44 am

Quote from: JohnFitz – August 03, 2016, 04:25:11 pm

Here's the DD "Turbo Technician's Guide":

John,

Thanks for pointing out the Turbo Guide - good clear photos and quick simple description of turbo function. I appreciate resources like that!

I know very little about turbos - our GV is the first "boosted" vehicle we've owned. I'm always on the lookout for info on new-to-me mechanical systems. I recently had the opportunity to view the "hot" side of our turbo, when I was working on our exhaust brake. I was pleased to see zero sign of blade to turbine housing contact. The blade spins freely with the slightest touch. Guess our turbo (180K miles) still has some life left in it.

Ken - good luck solving your problem. Sorry to say, but I think (just guessing) that signs point to a new (or rebuilt) turbo in your future.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #19 – August 04, 2016, 10:10:10 am

I know this is a different engine (Cummins 350 ISC) but with my Banks I see up to 32lbs on a good climb. One of the problems of lost Boost is also a damaged CAC.
JohnH

Re: 6v92 Exhaust Clamp Leak(s)

Reply #20 – August 04, 2016, 11:27:59 am

General ideas and things to look at:
Exhaust flow into the turbo clear
Exhaust flow out of the turbo clear
Turbo turbine clearance
No restriction of fresh air flow
Turbine blades on both side no damage
No oil from the bearing in the turbo passages
Waste gate inspection and operation
Charge air side leaks ( piping, air cooler, intake gaskets)

Most of this is fairly straight forward pressurize the charge air side to look for leak
Pressure the waste gate mechanism to make sure it actuates and does so at the right time

Re: 6v92 Exhaust Clamp Leak(s)

Reply #21 – August 04, 2016, 12:35:22 pm

Just an FYI on these 6/92's we don't have CAC nor waste gates.

at least not on these models.

Re: 6v92 Exhaust Clamp Leak(s)

Reply #22 – August 04, 2016, 12:50:08 pm

Granted, we all have different engines, and the turbos could be different. One thing Ken has not posted (or I missed it), is "are you burning a lot of oil?" I've blown two of them, and she sure sucked oil and smoked grey/blue, except in the high country in cold temps, where it was a cloud of white smoke!

Re: 6v92 Exhaust Clamp Leak(s)

Reply #23 – August 05, 2016, 10:32:13 pm

Quote from: mike leary – August 04, 2016, 12:50:08 pm

Granted, we all have different engines, and the turbos could be different. One thing Ken has not posted (or I missed it), is "are you burning a lot of oil?" I've blown two of them, and she sure sucked oil and smoked grey/blue, except in the high country in cold temps, where it was a cloud of white smoke!

Sorry just now getting back on. I've been down with a virus of some kind the last couple of days.

Think I'm about over it...

Haven't noticed using any oil. I'll keep an eye on it. No blue smoke only black. (and of course white at start up like all 6v92s)

I arrive into Denver on the 8th and have periodontal surgery on the 9th. Will probably be laid up for a week so won't get into S&S until the next week. Will post what we find.

see ya
ken

Re: 6v92 Exhaust Clamp Leak(s)

Reply #24 – August 06, 2016, 10:56:31 am

Heal up soon, Ken. Let us know what you find out about "the smoke".

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