5.7L Mercruiser Oil Leak-Valve Covers

[Maxum88]

I have a 1997 5.7L Mercruiser with Alpha One outdrive. The motor has performance heads on it (installed when I purchased the boat) and I'm leaking oil out of the valve covers. It actually runs out in a stream. The shop has tried just about everything...new gaskets, gaskets + RTV, customized valve covers, and just can't seem to stop the leak. Any suggestions? Thanks in advance.

 

[mattmullen]

When you say customized what type are they?

 

[Bt Doctur]

gonna need some pics cause those valve covers do seal

 

[Maxum88]

No Title

They said it was possibly the perimeter bolts that were causing the issue, but with fatter gaskets and rtv, it still leaks. As far as the type of heads, nobody has been able to tell me specifics. I'm trying to upload a video right now.

 

[boatman37]

are they stock sheetmetal valve covers? are they bent? i have had some that had a slight bend that required a little hammer persuasion to fix. if they are aftermarket then that may be the problem.

what brand are the heads? i have ran several different brands of aftermarket heads with no issues.

i have always tried to stick with fel-pro gaskets but have used others without any issue. i used to glue (with RTV sealant) the gasket to the valve cover but no sealant on the head side of the gasket. i was able to re-use them that way.

 

[Maxum88]

No Title

Rotate 90 degrees clockwise...I can't upload the video, but here's a screenshot of the oil coming out when the engine is revved.

 

[Bt Doctur]

perimeter bolts go in the edge of the valve cover, those covers have 4 bolts down the middle.Possable the wrong bolts are being used crushing the cover?

 

[Scott Danforth]

Most likely either a bent valve cover, or the RTV is causing the leak.

Your 98 would have perimeter bolts and would have come with rubber gaskets from the factory Straighten out the bent sheet metal, scrape all the useless RTV off them.

RTV has no place in a perimeter bolt valve cover (never had one leak yet......ever)

Get new rubber gaskets (recommend felpro) install, and go boating.

Heck, you can get cast aluminum valve covers, and new gaskets for under $80 and I guarantee no leaks

 

[Scott Danforth]

They said it was possibly the perimeter bolts that were causing the issue, but with fatter gaskets and rtv, it still leaks. As far as the type of heads, nobody has been able to tell me specifics. I'm trying to upload a video right now.

Your heads per the casting number are NOT performance heads. Just the same heads on nearly every 97 marine 5.7 liter

 

[Onexl85]

Those aren't perimiter bolts, they are center bolt heads that look like the perimeter bolts were shaved down

 

[Onexl85]

Has anyone ever seen a head like that?

 

[turbocorrado]

i had a similar issue and ended up with a bad valve cover, ordered a new one from chevy and it was dirt cheap

 

[flipbro]

Has anyone ever seen a head like that?

yup my boat has them. along with most 90s 5.7.

 

[Onexl85]

Your boat had the perimeter bolts shaved down?