Exhaust help

[Zilerobe]

Just picked up a 1998 Larson sei 206 fish and ski with a 5.0l VP and I was very excited about it. First time out on the lake it got hot. Like, just under pinned on the temp gauge (230-240). As soon as I noticed it I shut it down and pulled myself in with the trolling motor.

History of the boat is mostly unknown except that it hadn't been in the water all season. Started and ran on the hose flawlessly... never reaching full operating temp I suppose.

I went to my marine shop, picked up a new impeller and installed it that day. So far no more overheating problems. My concerns now are the residual problems. I started quite a dialog with the shop mechanic who has been very helpful but also left me a little skeptical.

I was told that at that temp the exhaust hoses were probably compromised and should be replaced. Ok, done. I was then told that the exhaust flappers probably fell out and are bouncing around in the y pipe or exhaust bellows and those need to be replaced. Well, I used this forum a whole lot in the last few weeks and I found the vp bulletin that said those aren't worth keeping/replacing, so nay. I was able to reach my hand down with the exhaust apart to feel that neither of those flaps were on their bolt. I can't be sure if this was of my doing this season or the flaps had already been removed. Another post here implied that unless your getting performance issues don't bother searching for the flaps until your next stern drive drop. So I didn't.

This last time on the lake I was accelerating and felt a bog. I came back down to idle and took off again with no problems multiple times. I opened the engine compartment at idle to find water leaking around my port side manifold. I am confident this was not there before as I studied the engine for leaks after replacement of the hoses. I'd like to think it's just a gasket but does anyone think it could be caused by the back pressure of a loose flap?

First thing I checked when I saw water leaving the engine was the oil and it was still golden.

So, basically I'm asking what should I do. I'll be able to take the manifold off sometime this week (any tips on not breaking bolts would be much appreciated). Should I look for the flaps? Can I do that without removing the out drive? And finally, is there anything else I need to do post overheat to proactively prevent malfunction? I hit the lake and it's more worry than enjoyment anymore. Thanks everyone.

 

[bruceb58]

I would pull the outdrive anyway just to check the u-joints and see if there is water in there. You need to pull the outdrive eventually to check that. If you don't know the age of the u-joint bellows also replace that.

Your water leakage probably has nothing to do with the flappers assuming you covered the holes for the flappers when you replaced your exhaust hose off the riser.

 

[Scott Danforth]

welcome aboard

 

[Bondo]

I opened the engine compartment at idle to find water leaking around my port side manifold. I am confident this was not there before as I studied the engine for leaks after replacement of the hoses. I'd like to think it's just a gasket

Ayuh,..... Welcome Aboard,..... Is this at the manifold/ riser connection,..??

If so, ya oughta get on it, Sooner, rather than later,....
If it's leakin' out into the boat, it's also no doubt leakin' In, into the motor,....
It could be the cause of the bog ya had,....

If in saltwater, it could already be too late,...
Ya gotta get the motor runnin', 'n dried out,....
It's a straight shot down, from that gasket to the 2 center cylinders,....
Water means rust, which will lead to needin' a new motor,...

 

[Zilerobe]

Thanks for the responses. It is not the manifold-riser connection. Actually, I failed to mention that I replaced those gaskets with the exhaust hoses. Also, I am only in inland freshwater lakes. I dropped it in the lake today and watched more closely for the leak. It is at the center two cylinder exhaust outlet to the manifold. I'm ordering a new gasket and bolts for it now. Im trying to connect this predicament to the overheating event. Am I thinking too hard? Expansion weakened the seal between the head and manifold? I will report my findings when I remove the exhaust.

 

[bruceb58]

If you have water at the head/manifold junction, you have big problems as there is not supposed to be any water there.

 

[Scott Danforth]

Thanks for the responses. It is not the manifold-riser connection. Actually, I failed to mention that I replaced those gaskets with the exhaust hoses. Also, I am only in inland freshwater lakes. I dropped it in the lake today and watched more closely for the leak. It is at the center two cylinder exhaust outlet to the manifold.

if you have water at the center two cylinders at the cylinder head, you have a leak at the manifold/riser connection, or your risers are too short for the installation. you have water coming into your motor.

 

[Zilerobe]

I pulled the manifold off today and there was some water at the bottom and in the head. Still only the center cylinders and I didn't see any good evidence of water from down the riser or riser gasket. Could overheating crack a manifold and cause water there?

 

[jerryjerry05]

When posting include model#s and anything that will help identify your motor.
They made about 25 different models of 5.0 in 98
They didn't put exhaust flappers in all exhaust systems.

The riser/ manifold.It's 17/18 years old.
Even in fresh water they go bad.
Not sure when Volvo started using Chinese parts but yours might be Chinese junk???

IF??? Your getting water in the manifold then the risers are probably shot???

 

[Zilerobe]

No Title

Pulled this out this morning. No obvious cracks in the heads or block so far. So it could be worse.