Gm 165 inline 6 with water in engine.

[sculbert]

Hi guys, I'm new here but am greatly impressed so far. I have a 1979' 18' Chapparal, I have swapped out my 153 4 cylinder with a used inline 6 250cid 165hp. I got it running yesterday and have found water in the oil. I have run compression test and all cylinders are between 155 to 175 compression. I took off the manifold and found water laying in the exhaust ports of the manifold. My gut feeling is the engine is okay. I think I will take the head off and replace the gasket because two cylinders are 155psi and they are number 5 and 6 probably a head gasket gone bad. All others are 175 or a little better compression. <br /><br />My question is; What is the best option for the manifold? will it cause water in the oil? Please give some good options so I can move with getting this thing running. <br /><br />Thanks! PS... If the recommendation is replace the manifold is there a better deal over another like headers or something else.

 

[yoced]

Re: Gm 165 inline 6 with water in engine.

Yes, you can have water in your engine from this manifold - in fact it is quite common with this manifold.<br /><br />Take the manifold off and look inside for cracks and holes. First look for vertical cracks in the two exhaust ports which surround the center intake port. Next most common failure would be the surface between your manifold and riser.

 

[sculbert]

Re: Gm 165 inline 6 with water in engine.

SO from what I have seen on this board it is best to replace the unit instead of trying to fix it if I do find a leak. Is there any better option than going back with another cast iron, or should I drain the manifold after every use to keep water from sitting in it when not being used?

 

[sculbert]

Re: Gm 165 inline 6 with water in engine.

Yoced your correct. The manifold is cracked right in the middle under the carb bleeding down into the exhaust chamber. Well I am in the process of ordering a new manifold and riser. I figure I should start off new all the way around since I noticed alot of scale on the riser also.

 

[nickwilson]

Re: Gm 165 inline 6 with water in engine.

Don't try to fix them, get a new one. If you replace the manifold replace the riser too. I found new manifold for my old 165 for about 400 bucks. The riser is only 100 more. You'll have it all apart anyway so just replace both. If you haven't had it apart yet, the manifold and riser come off really easy on the 165. You could probably do the entire job in 1.5-2 hours - maybe quicker. I looked all over and the best price I found on th NEW manifod/riser(don't get a used one) was at boatbandit.com - part # OSCO 8759 (manifold) and OCSO 6351 (riser. Anyway, hope this helps...

 

[DJ]

Re: Gm 165 inline 6 with water in engine.

Replace the manifold with a stock type. Look here.<br /><br /> http://www.iboats.com/boatproducts/mallsearch/manifold/

 

[nickwilson]

Re: Gm 165 inline 6 with water in engine.

I hate to be the one to bring this up, but it doesn't sound as if we have eliminated the possibility of a cracked block. Compression can be fine but there still be a crack in the water jacket somewhere. I would check on this before I spent $$ on a manifold replacement.

 

[sculbert]

Re: Gm 165 inline 6 with water in engine.

I hope your wrong about the block, I got a little bold and ordered the manifold! $526.00 with riser and gasket set. I did go out and by a head gasket and am getting ready to pull the head to have a look see since I am almost there any how. <br /><br />Pray for me please.