6v92 sweet smelling exhaust

[Jim saco]

The last time I used my 41c I smelled coolant coming from the star. side exhaust. I thought I had smelled it earlier in the season but my coolant level was never low. On the last 2 runs I lost about 1 gallon. My mech. came and advised on not using the boat. After waiting 2 weeks for him to get time to pull it apart I got impatient and pulled my exhaust manifolds off. I found the tell tail sign of water " white and clean" coming from my outboard rear cylinder exhaust port on the head. How much work is it to pull the head off? I called my mech. and he tells me that's the next step he also told that he can put it back together if I can't. He's saying all it takes is time and money. If I take this head off what can I expect? This is my first time doing anything major on a diesel.

 

[saltshaker]

Are you positive it is from the head and not the exhaust pipe? If the riser leaks it will run down to that same spot. I had the exact same problem on a 6V92. I also figured it was from the head but it turned out to be a pin hole in the exhaust riser.

 

[dsharp]

If it's burning antifreeze it has to be leaking in the system before it gets to the riser. It is usually better to pressure test the manifold before you start taking the engine apart. You can usually rig something up with pvc fittings and a gauge and schraeder (tire) valve. As far as difficulty, it's not really hard it just takes bigger tools and a couple of people to lift the head off. Be very careful with the head, they have have machined edges that can damage your hands pretty badly if it gets away from you.

 

[rsmith]

A good radiator shop should be able to press test your manifolds. I was losing water in my 12'/71's and pressurised the system cold and found the injector tubes were leaking. If you get one of the slant testers you pressurise the system your self.

 

[saltshaker]

If it's burning antifreeze it has to be leaking in the system before it gets to the riser. It is usually better to pressure test the manifold before you start taking the engine apart. You can usually rig something up with pvc fittings and a gauge and schraeder (tire) valve. As far as difficulty, it's not really hard it just takes bigger tools and a couple of people to lift the head off. Be very careful with the head, they have have machined edges that can damage your hands pretty badly if it gets away from you.

Not in my case. The leak was in the exhaust riser. The coolant was burning off when it hit the hot exhaust. Visible white smoke and the sweet smell of antifreeze. You might get small amounts into the cylinder that will be burned off while the engine is hot. The problem arises when the coolant leaks into the cylinder when at rest. He may have a leak that is only evident while the engine is hot and running. Mine closed up when the engine cooled down making it extremely difficult to find.

Jim I wouldn't pull the head unless you are certain that is where the leak is. Any overheating or high running temps? How many hours on them?

 

[Jim saco]

The manifolds look ok that's not to say that it's not the problem however they are lower than the heads. It seems that the manifolds would have to fill up for it to get into the cylinder. At least when the motor was at rest. The coolant is evident in the exhaust as soon as it fires there's not much of any smoke just a light steam and that sweet smell. The motor never ran over temp atleast it never has since I've owned it. The motors have 300 hours after an inframe was supposedly done. I've owned her for about a year now. The po had enough receipts to make me and my mech believe it had been done. I feel confident I can remove the head without damaging it However I don't want to remove it if it doesnt have to come off. If the leak was in the exhaust down stream from the head and the motor was burning it off why would I have evidence of water on the exhaust port without the motor hydro locking? I never had any sign of it laboring during start up.

 

[saltshaker]

My entire engine still looked new including the exhaust components. I had less than 1000 hours SMOH. Mine leaked from the riser that comes off the back of the manifold up to the turbo. I assume you have wet turbos on an '89 boat. The coolant may not be getting into the cylinder. You may be dumping it out the exhaust. It might get in the cylinder while running and it is being burned off. the danger is if it does leak down into the cylinder while at rest you could end up with hydro lock. Take off the turbo and look down the exhaust with a scope. See if you can find a point of origin or trail from a leak. The pin hole in mine wasn't visible but the trail was. Everyone thought mine was from the head gasket or a cracked head as no other signs of a leak were found. My entire exhaust was removed , reassembled in a shop and pressurized. No leaks found. The head was fine. Mine only leaked while engine was hot. No sign of a leak while running at cruise or at low temps. After the engine was stripped to the block and rebuilt, the leak was still there. That's when they went back to the exhaust again and found the trace of coolant. The mechanic was able to patch the leak as a temporary fix. Ordered a new riser and no more leak.

 

[Will]

This thread covers some options on checking exhaust manifold without removing it from the engine.
"Need help - DD6-71 coolant issues"
Will

 

[Jim saco]

Jack Thanx for your replies. I'm going to try and Jimmy some fittings up and pressure test the outboard side with the head in place. I hope it's in the exhaust. That would be the easiest option at this point. I dropped of the manifold and riser that connects the manifold to the turbo collector. If it's in the exhaust it will be in those 2 items. The turbo on this model I believe to be dry. I could be wrong. I wouldn't know the difference. My turbo has oil lines running to it and is before the shower head. Can someone tell me what the difference would be between wet and dry turbo's?
Thanx

 

[saltshaker]

Jack Thanx for your replies. I'm going to try and Jimmy some fittings up and pressure test the outboard side with the head in place. I hope it's in the exhaust. That would be the easiest option at this point. I dropped of the manifold and riser that connects the manifold to the turbo collector. If it's in the exhaust it will be in those 2 items. The turbo on this model I believe to be dry. I could be wrong. I wouldn't know the difference. My turbo has oil lines running to it and is before the shower head. Can someone tell me what the difference would be between wet and dry turbo's?
Thanx

Do you have exhaust blankets? A wet turbo is cooled by the FW side of the engine. The exhaust riser would also be water jacketed. The wet turbos have a single large turbo.

 

[Jim saco]

Jack thanks there is one turbo on the engine and it does have coolant lines going to it. After the exhaust leaves the manifold it hits the risers all of this has antifreeze in it . I have both of those off and see no signs of water. I can look into the pipe that connects the 2 risers together which also holds the turbo. Nothing on this engine see's raw water. I guess it's a good thing except when your chasing a coolant leak. I think I have what I need to put pressure on the out board side including the head. I'll let you know how I make out .

 

[saltshaker]

That's a wet turbo. Pressurize with air and see if they hold. Did you remove the exhaust manifold also?

 

[Jim saco]

Jack both manifolds and risers are out and i dropped off the outboard manifold and riser to get tested but no word back yet I put pressure on the outboard side of the engine and leftover coolant and air came shooting out of the exhaust port on the rear cylinder. At this point I'm confident it's in the head. With the amount that shot out with what little pressure I put in " around 10 psi" I'm lucky the cylinder didn't fill with water. I believe that I would have blown this engine if I had continued to run it. I hope I dodged a bullet here. I'm going to attempt to pull the head. I combed thru the service manual and it seems possible for me to get it off. Putting it back may be a different story. Jack thank's for the help I'll post back how I make out. I've taken a bunch of pictures and ill see if I can post a couple if I can figure out how to get them out of the iPhone. and on the site.

 

[saltshaker]

good luck and be careful. The heads are pretty heavy. Make sure you can handle them and have adequate room to maneuver, particularly since it's the outboard side. With the head off you can take a good look at the cylinder to make sure there isn't any damage or excessive wear.

 

[mr hatt]

If no one has pointed this out I will. If someone has them sorry for the repeat. The 92 series has no tolerance for glycol in the oil. Make sure you don't have any in your oil our you'll spin a main bearing in a heartbeat. If your not sure have an oil analysis done. Hopefully the problem is in a head or the exhaust. The reason I say check your oil is to see if you might have a liner leaking. Just my two cents any probably not even worth that. Good luck.

 

[saltshaker]

If no one has pointed this out I will. If someone has them sorry for the repeat. The 92 series has no tolerance for glycol in the oil. Make sure you don't have any in your oil our you'll spin a main bearing in a heartbeat. If your not sure have an oil analysis done. Hopefully the problem is in a head or the exhaust. The reason I say check your oil is to see if you might have a liner leaking. Just my two cents any probably not even worth that. Good luck.

A great point and one I'm embarrassed to say I forgot to mention. I know we suggested checking the oil for contamination but never suggested the oil analysis. This should be down before you start tearing it apart. Only problem is he can't run it to warm the oil but I think coolant should still show in the sample if there is any. I believe a leaking injector tube can also dump coolant into the oil.

 

[Jim saco]

The head is off and it wasn't as hard as I had expected it only took 4 calls to my mech and 4 hours of my afternoon. Also the skin on most of my knuckles. It is extremely heavy and I bribed a friend to help get it out of the engine room. The outboard side of this boat a terrible spot to have to work I now know why my mech. doesn't want to work on pleasure boats. The head has no apparent signs of failure but the cylinder looks clean. Ill drop it off at a machine shop to have it tested. When my mech came out the first time he tested the oil and said it was negative for coolant he told me if coolant was sitting in that cylinder it would have gotten by the rings and showed in the oil. I was nervous because I realize that any internal coolant leak these engines usually doesn't turn out well. I'm the type to figure for the worst and when something isn't as bad as I expected it's a good turn out. I'm still at the boat so I can't post pics.

 

[saltshaker]

Any signs of a gasket leak or crack in the head?

 

[Jim saco]

I didn't see any cracks or area of failure. I dropped it off at the machine shop and was told they are slow and could get on it this morning. I think it's going to be cracked I saw in the service manual that if it was a poorly seated injector sleeve that I would have had bubbles in my overflow because of compression gases leaking. I'll post again when I find out more.

 

[garyd]

Well what the heck happened??