sonic28

ok guys I listened to you all I thank you as always the problem was the headers two sets brand new CMI headers and both pair leaked.now a new problem blow by pushing the dip stick out.I did a compression check 170-175 all eight cyls did a leak down 3% seems good.the water that was in the oil from the headers where flushed three times with a 25% mystery oil and reg oil.what will cause this blow by.the engine is running smooth.

Ted G

iTrader: (1)

Some engines seem more prone to it than others, We had 3 doing it after rebuilds to 540ci on a 47 Fountain. Installed springs on the dipsticks to keep them down. No real problem with the engines, I think the loading the boat puts on it just causes too much crankcase pressure and not enough venting to handle it.

Raylar

Tell us a little more here. Merc HP525EFI's? or some other build out. Whose cam and detail the rest of the exhaust, Captains Call? S-Pipes, Muffler, ETC? Intergrated transom on boat with exits under the platform? Do you idle a lot, back down hard? Have you pressure tested the headers?
Not enough real info here to render a good opinion!
Water in headers that's getting into crankcase will cause a lot of painful issues and crankcase pressure can be one of them.

Regards,
Ray @ Raylar

sonic28

hi Ray
third set of headers from CMI the original had a leak the new ones from CMI also had a leak finally no more leaks.the motors are stock 525's this is port motor.The boat is 2004 fountain lightening all stock yes it does have silent choice but always left on.

sonic28

please !!!!!!!!!!!!!!

outriggers

The boat is 2004 fountain lightening all stock yes it does have silent choice but always left on.[/QUOTE]

Left on? On like through hull or on like through the prop? Doug

Raylar

Sonic 28:

Are these engines in this boat a side by side or staggered setup?

Are your tips attached to the headers a custom shape and are you using CMI's switchable exhaust or someone elses?

If you can, take some pictures of the installation and post them here so we can see the setup.

If these are stock HP525's, the CMI's are Mercury's design and they should have been fine from the get go originally. Now that you are sure the leaks are stopped, and obviously some good oil changes to get all the water out, what is telling you that you are still getting water in the engine?

Have you pressure tested the closed cooling system at about 13-14lbs abd made sure you don't have some other point of leakage?

Just some more questions to help with your investigation and hopeful repair.

Regards,
Ray @ Raylar

sonic28

hi guys
the engines are staggered yes its all cmi with cmi silent choice. when I say open I mean thru transom.yes
i did do a preasure check on the closed system as well.
i beleive the water in the oil thats left was from the journals and will go away after a couple more flushs.Why and where could the blow by come from a crack in the piston when hot?could I have cracked it when the engine was hot and the water hit the piston if so why didn;t i suck a valve. When I run the boat its smooth no miss fire or skips.

















i

blue thunder

Are these engines equipped with PCV valves? If not that should help you a bunch. Also if you have not, I would get the engines good and hot a couple times, maybe your blowby will subside.

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