Leaking Exhaust Manifold

[jatton]

Hi All,

I'm trying to figure out what is causing a water leak on my 787 engine. 1997 GTX that has a leak between the lower end of the exhaust manifold and the cylinder. It's a fairly steady stream of water that starts immediately upon engine start, whether hot or cold. It's not coming from the bolt hole, it's actually from the surface between the two pieces.

I have removed, cleaned, and replaced the exhaust manifold several times trying to re-seat the faces with no luck. Brand new gaskets on. Both the exhaust manifold face and the cylinder face appear to be flat but I'm still getting a leak. Torque on the bolts is good. I don't want to go any tighter out of fear or stripping something.

Anyone experienced this or have any thoughts as to what could be causing it?

Thanks.

 

[jatton]

I know it's a bad photo but this shows where I'm talking about. It's right near a bolt, but not coming from the bolt hole itself.

 

[racerxxx]

There are plugs on the underside just like the ones on the top side that are welded on. They rot out and need to be replaced. I make replacement ones that have to be welded in like the original ones. Shipping is now $6.50 but the plugs are still $5 each.

https://www.seadooforum.com/showthr...st-plug-cap-or-whatever-you-want-to-call-them

 

[jatton]

Thanks very much. I'll go pull it and take a look this afternoon. I have had the plugs on the exhaust pipe go and repaired those, but didn't know there were ones in the manifold piece.

 

[jatton]

Is the plug on the cylinder jug or the exhaust manifold?

 

[racerxxx]

No, there are none on the manifold. I couldn't see in that pic, I just assumed you meant the exhaust pipe, not actually the manifold.

 

[dieselndoo]

^^^ why assume? Clearly posted in the start of 2nd paragraph, EXHAUST MANIFOLD...

OP, is the paint on the head bolts untouched? If not, you may need to remove the head and loosen the cylinder hold down bolts, then armed with new manifold gasket and it wouldn't hurt to lace it with sealant/gasket maker, on both sides of gasket, to install then, the manifold then tighten down cylinders

 

[racerxxx]

^^^ why assume? Clearly posted in the start of 2nd paragraph, EXHAUST MANIFOLD...

OP, is the paint on the head bolts untouched? If not, you may need to remove the head and loosen the cylinder hold down bolts, then armed with new manifold gasket and it wouldn't hurt to lace it with sealant/gasket maker, on both sides of gasket, to install then, the manifold then tighten down cylinders

Hey thanks, I missed that. I'll never assume again.

 

[Spimothy Leary]

I'm not much of a wrencher but that seems like an odd spot. The pic didnt help me, it confused me. However if you determine its the manifold the good news is they are dirt cheap, I have several of them that just sit in the attic because they generally cost more to ship than they are worth.

 

[jatton]

Thanks everyone for the input.

Nope, the cylinder head bolts are not untouched. I'll try renewing the gaskets and tightening to see what that does.

Sorry for the confusion on the photo. Not a great shot, I agree. I'm going to try renewing the gaskets and going from there. I suspect I may have been wrong about it coming from the exhaust manifold-to-cylinder jug face. The cylinder jug-to-crankcase face is right there at the same spot also which may also be the culprit.

On the topic of gaskets, I'm hoping someone can clear up some confusion on my part. The current gasket between the crankcase and the jugs has 6 holes and is very, very thin and green. When I look up the part number on brp's website it give me 5 options. 0.3, 0.4, 0.5, 0.6, and 0.8 mm thick. Only the 0.4 and 0.6 mm gaskets are available though. SBT's website doesn't specify which one it is but shows a 5-holer in the photo. Which one should I use?

 

[racerxxx]

Thanks everyone for the input.

Nope, the cylinder head bolts are not untouched. I'll try renewing the gaskets and tightening to see what that does.

Sorry for the confusion on the photo. Not a great shot, I agree. I'm going to try renewing the gaskets and going from there. I suspect I may have been wrong about it coming from the exhaust manifold-to-cylinder jug face. The cylinder jug-to-crankcase face is right there at the same spot also which may also be the culprit.

On the topic of gaskets, I'm hoping someone can clear up some confusion on my part. The current gasket between the crankcase and the jugs has 6 holes and is very, very thin and green. When I look up the part number on brp's website it give me 5 options. 0.3, 0.4, 0.5, 0.6, and 0.8 mm thick. Only the 0.4 and 0.6 mm gaskets are available though. SBT's website doesn't specify which one it is but shows a 5-holer in the photo. Which one should I use?

Obviously with everything painted black someone has been in there but I don't want to assume. The "rule of thumb" is you put back in the same gasket that came out. So if it's a 6 holer, that is what you put back in. If you want to check it you can use a piece of solder and do a squish test. The procedure is in the service manual. Just make sure you put it in parallel with the wrist pin and check the squish on both sides of the pin. Now..............chastise if you like.............You can just put a 6 hole or 5 hole back in and call it a day. On a standard engine you will notice/feel ZERO difference while riding it, if anyone can I'd love to meet them, it's not gonna run different at all. You're changing the port timing by such a minute amount, but....going too small you are essentially bringing the piston closer to the dome and could possibly get detonation. But for your application just go with the 6. Like you saw, SBT only sells the bigger ones.......do you really think they're that lucky and manage to get all the engines from seadoos that only had 4,5, and 6 hole base gaskets?

I put 2 engines in a Challenger a few years ago and 2 years later they guy had a base gasket that leaked. SBT puts so much sealant on the base gasket I'd bet it was like a 12 holer when they torqued it down it was so thick. I still have it as a souvenir.

 

[dieselndoo]

I deal with 3 engine builders. None, paint their engines black. So, to no fo-sho, is the base gasket visibly green? Have you removed the head/raves to verify .25 .50 or...81.89(OEM)....etc. Whatever mother were talking about... Here a tidbit from a builder... S.B.T. engines have milled combustion chambers to prolong the life of poor quality parts

 

[dieselndoo]

Possibly, previous owner was going fur a "murder" look, and decided to remove the mother and paint it...