Hot Exhaust Manifold and Elbow

[milkyway]

1999 Alpha v8 220 hp.

I removed the exhaust manifold with the elbow because it was getting so hot. Ran water hose at all openings and passages of the manifold and elbow and all were clear. Water hose from the thermostat to the manifold is also clear. Exhaust pipe shutter is also intact and flapping without issue.

Reinstalled the pieces and checked volume of water at the end of the hose going into the manifold. Volume is excellent and the same as the hose at the port side.

I have owned this 1999 boat since 2004 so I don't know if the manifolds have been replaced by the original owner.

Before I buy a new set to replace the ones I have now and which I have proven to be all clear, would there be any other causes of manifold and elbow overheating?

Thanks.

 

[Haut Medoc]

Re: Hot Exhaust Manifold and Elbow

This is a raw water system, correct?....
Is it possible that when you removed the man/riser that you dislodged scale from the water dumps on the riser?......
They are not big & are the only way for water to exit....
I'd think about replacement esp since you are in salt water.....
I've seen aftermarket mans/risers for $369 on ebay (both sides)for that price.......​

 

[Don S]

Re: Hot Exhaust Manifold and Elbow

Have you changed the raw water pump impeller? If so, did you get the blade of the impeller turned the right direction? If not, the Gen II impellers will not go the right direction and can cause an overheat.

 

[milkyway]

Re: Hot Exhaust Manifold and Elbow

Thanks.

Yes, it is raw water and on salt water. Some rust came out during hose flushing and I even scaled the passages with small screw driver. I ran a garden hose at full open to all wide passages at the manifold and elbow at all directions and did not observe any water backup. Water flowed continuosly to all exit points. I expected some restriction and would have justified replacement. That's the easy part.

Am I missing anything other than inkling to replace the parts?

 

[milkyway]

Re: Hot Exhaust Manifold and Elbow

I replaced the impeller this June 2007. Last time was 2005. Water flow at the hoses ( feeding to the manifolds) at both star and port sides are 100% excellent and the same volume.

 

[milkyway]

Re: Hot Exhaust Manifold and Elbow

Replacement is the final alternative? Anyone?

 

[Scaaty]

Re: Hot Exhaust Manifold and Elbow

Replacement is the final alternative? Anyone?

Yep...raw water cooled in salt have a life span of 4 years or so without using a fresh water flush..you are due for replacement

 

[milkyway]

Re: Hot Exhaust Manifold and Elbow

I guess replacement is the only solution to this obvious problem.

 

[party barge]

Re: Hot Exhaust Manifold and Elbow

Have you changed the raw water pump impeller? If so, did you get the blade of the impeller turned the right direction? If not, the Gen II impellers will not go the right direction and can cause an overheat.

Don, I don't know if you remembered my overheat situation but I noticed the sound of the new rebuild changing pitch of the engine sound and realized afterwards that it was starving at times for water. I cooked it all...I see you say here that them blades have to be in a certain direction..can you tell me what direction they should be in...I bet this was my problem. The motor sound was when it got to starving for water it would get rumbbley, sorta hotrod sounding at times for very short periods...everything was new too, everything...if this impellor was on wrong I'm gonna flip out.

 

[Don S]

Re: Hot Exhaust Manifold and Elbow

Party Barge, start a new thread. Reference this thread if you want, but don't ask your question on Milkyway's thread.

 

[party barge]

Re: Hot Exhaust Manifold and Elbow

Sorry, I didn't think I hi jacked it since the answers for him led right into my subject....It seemed to me we may have had a same problem and since the thread was a few pages in and was gone I thought I'd revive it instead of talkin the same ole subjects again fatiging people...I didn't know threads here were to be for one person only. It would seem to me if 6 guys have the same issue why couldn't they all chime in....when they don't guys say "there are threads on this allready, the subject has been talked about, go dig" LOL

From now on I will start new ones no big deal...I just gotta learn the manorisms here is all sorry