Water leaking from exhaust valve HELP!!!

[GA_Boater]

I sure do why what are you thinking?

It seems the guy working on the head isn't the best from looking at your later posts. He should know the guides go through the water jacket and any special procedures to replace the guides. You're paying for him to learn!


Since you're concerned about the quality of the work being performed, If I was you, I would take it to a Chevy dealer. They have access to parts and they are trained to work on GM stuff. They may also warranty their work.

Another thing - Combined both threads. Lack of thread history causes untold problems and duplicate advice.

 

[cableguy1979]

Looks like both threads have been combined.c My bad I thought i was saving a problem and confusion.

 

[Scott Danforth]

as I said, the 088 heads are a dime a dozen.

https://www.google.com/search?q=14097088+craigslist&ie=utf-8&oe=utf-8&client=firefox-b-1-ab

same rectangular port head that Mercruiser puts on the 425hp 502. its the crate motor head

your in the middle of Tennessee, there are hundreds of good machine shops there that build race motors, boat motors, etc.

 

[tpenfield]

One interesting thing to note is that the 088 heads seem to be a bit more pricey than other BBC heads.

probably still find some that would be a better deal than rolling the dice with a machine shop trying to fix a rusted out head.

 

[cableguy1979]

Ill call around today. Nothing on CL or eBay that's reasonable. Ill call machine shops today but I dont believe my heads are rusted. Its a 666 hour fresh water engine and the valve guide was broken it wasnt pitted or eaten up at all. Any clue how a valve guide breaks?

 

[cableguy1979]

Called 32 boat places or machine shops and not one has a set of 088 heads. At this point Im gonna hope mine can be repaired.

 

[tpenfield]

If in fact the guide itself became cracked, yet the head casting can be verified as still good, you could do a repair/rebuild on the current set of 088 heads. Best to have a good machine shop that has seen a few 454 heads in their day, rather than one asking a bunch of questions.

When I brought my 454 heads in for some work, the machinist warned me about the rust through, given that the guides go through the water jacket. He was right :faceplam:

You can always have the heads pressure tested to make sure all is good.

 

[cableguy1979]

All true. He has pressure checked the heads and the only leak so far is this valve guide. Hes supposed to replace the valve guide with the new one today. Ill let you know how it goes.

 

[hogbare35]

Cable, call Johnny @ cylinder head service in Fairfield Al (Birmingham) .Ive been using him for years. Knows his business and reasonably priced, very good supply of heads.

 

[Scott Danforth]

One interesting thing to note is that the 088 heads seem to be a bit more pricey than other BBC heads.

probably still find some that would be a better deal than rolling the dice with a machine shop trying to fix a rusted out head.

the 088 is a "crate-motor only head" for the GM performance product HO 454 and 502 (not the ZZ454 or ZZ502 as those received aluminum heads with 110cc chambers) as standard production for automotive (Truck) was the L19 in the (4500 and larger trucks) and L29 vortec heads (found in the 2500/3500 trucks) . both the L19 and L29 heads are oval port. since the volume is lower, the price appears to be higher. the majority of use is Mercruiser assembled 7.4 and 8.2 motors since the automotive guys and the merc racing folk use aluminum heads.

as far as heads go, the 088 head is specific to the Gen V (steam port location) and can also be used on the Gen VI as teh block steam ports were opened back up. they are a revised version of the 188 heads (steam ports moved) which are an update of the 049's from the 70's

side note the stock merlin 269cc oval port head out-flows a mild ported 088 head by an additional 20% up to about 6000 RPM. the 088 heads really only help the 454 in a boat from 4000 - 5200 RPM over the smaller production oval port. they do hinder low to mid-range power. the Merlin 310cc rectangular port heads flow 50% more than the 088's and are considered a good upgrade to the stock heads.

 

[cableguy1979]

Ok Im very interested in better heads but Im not familiar with Merlin heads. If I replace the heads do I have to do any computer work? Thinking about replacing the cam and lifters while im in there but dont want to get into reprogramming the computer. If i just replace heads will that have to be done?

 

[cableguy1979]

Actually lloks like those heads are quite pricey!!! Ill just stick with stockers.

 

[cableguy1979]

Gonna be putting the engine back together and if this was a car engine I would put permatex on the water jackets of the intake and of the front and rear seal would be complete permatex instead of using the gaskets provided. Since this is a marine engine I wonder if I do the same thing? The water ports on the gaskets initially didn't have it so should i this time?

 

[Bt Doctur]

Permatex Aviation on the water ports and RTV on the front and rear areas of the intake

 

[cableguy1979]

Really! I really expected for someone to say DONT put sealant on the water ports of a marine engine! I have read that most say to put it on the way a manufacturer does for a marine engine. However BT i trust what you say so Ill give it a try.

I have never heard of permatex aviation. Where can I find it?

 

[cableguy1979]

OK I finally got it all put back together and ran the engine. Idles around 800-850 RPM which I believe to be correct. Sounds good. Doesn't seem to have water in the oil now and appears to all be well. With that said I have a few questions Id like to see if i cant clear up. It idles fine but when i rev the engine it only settles back down to 1000 RPM until I shut off the engine. It will then start back up and run at 850 RPM. What could cause this? Throttle cable? IAC?

Next what is the average running warmed up engine temp? Mine runs about 160 165 on the hose? I ask this because the intake gaskets had blocked off the back ports for water flowing. Is this normal for a marine engine and why?

After it has had some run-time in the driveway I will do a compression test. Next ill put on the outdrive. Anyone know how hard it is to replace the shift cable going down to the foot? Easy on a Alpha but what about the Bravo? Procedure or write up?

Decided to run a quart of Marvel Mystery oil through the engine oil and fuel system. Snake oil or worth it? Planning on squirting some in each cylinder for hoping to lubricate rings and cylinder since its been so long.

 

[tpenfield]

idle should be around 600. T-stat is a 160, so the temperature sounds right.

Water flows from the cylinder heads to the front of the intake manifold to the t-stat housing.

There is not a water duct at the rear of the intake manifold IIRC, auto or marine 454.

You'll need the adjusting tool for the shift cable replacement. Refer to the Mercruiser Bravo service manual for detailed instructions. Not the easiest thing in the world, but do-able with the special tools.

If MMO makes you feel better, then it did its job.

 

[Rick Stephens]

MMO is adding a lot of detergent to oil or fuel. I like it for some things. Surely can't hurt an engine that's been sitting. I mostly like to add it to fuel injection.

 

[AlabamaNewbie]

Cable, call Johnny @ cylinder head service in Fairfield Al (Birmingham) .Ive been using him for years. Knows his business and reasonably priced, very good supply of heads.

If you find yourself back in a head or engine situation, I concur with hogbare - call Johnny @ Cylinder Head Services. If he can't fix it, then it can't be fixed. If he can't find you a reasonably priced replacement - its because one doesn't exist in the galaxy.

 

[tank1949]

Any other possible cause?

U didn't say if it was a salt water boat or raw salt water used to cool it. If you have been running it in salt water and cooling it with salt water, get ready to buy another motor and manifolds. 22 years is a long time pumping salt through it. If it is a fresh water boat, I suspect water is getting sucked into valve from another intake port near water passage. Been there too! U need to pull exhaust manifolds and risers and then fasten a garden hose to motor to isolate leak. U may have run boat hot and blew gasket as others have suggested. Good luck!