Removing Cylinder head from 350 Mercruiser

[lenny2113]

After finging out that there is no compression in 2 cylinders I want to remove head to inspect valves, pistons, cylinders, etc. <br /><br />I need to take the cylinder head off (one side only). <br />Correct me if I'm wrong:<br />1) Drain exhaust manifold<br />2) Remove riser elbow<br />3) Remove exhaust manifold<br />4) Remove carburetor<br />5) Remove intake manifold<br />6) Remove valve cover<br />7) Remove head cylinder bolts and pull head<br /><br />Am I forgetting something?<br /><br />Thank you.

 

[The Marine Doctor]

Re: Removing Cylinder head from 350 Mercruiser

Depending on which side...you might have to remove the powersteering pump or the alternator. As well as the T stat housing might have to be removed.<br /><br />TMD

 

[DJ]

Re: Removing Cylinder head from 350 Mercruiser

You can probably leave the carb. attached to the intake, save yourself a gasket. Unles, you're going to rebuild the carb anyway.<br /><br />The same holds true for the exhaust manifold/riser. It's a lot easier to deal with corroded bolts on the bench than in the bilge.

 

[wmorris]

Re: Removing Cylinder head from 350 Mercruiser

don't forget to mark the distributor before taking it out of the intake to save time during installation and be sure to remove and install the head bolts in sequence. a service manual is invaluable.

 

[lenny2113]

Re: Removing Cylinder head from 350 Mercruiser

I will get Mercruiser OEM manual for a 350 engine tomorrow morning and read about sequence of bolts for a head. I know it is important and I have no clue to it as of yet. <br />It is the left side manifold (if facing engine). <br />I assume I do need to take off exhaust and elbow prior to taking off intake manifold.<br /><br />Thanks for your feedback.

 

[Lake Rat]

Re: Removing Cylinder head from 350 Mercruiser

You'll also need to loosen or remove the rocker arms and remove the pushrods. If you need to remove the lifters(you shouldn't need to)be POSITIVE they go back into the exact spot they were removed from.<br /><br />Best of luck!<br /><br />John

 

[lenny2113]

Re: Removing Cylinder head from 350 Mercruiser

Finaly, I took it off today. Owner of the marina offered to come work for him during next summer. <br />I found that the head gasket is blown between the 2 cylinders closer to stern. It is on the left side of the engine (facing engine). Those are the cylinders that had a lower compression then the rest. <br />Can blown head gasket be the cause for lower compression reading? <br /><br />Thank you

 

[flashback]

Re: Removing Cylinder head from 350 Mercruiser

absolutly!

 

[lenny2113]

Re: Removing Cylinder head from 350 Mercruiser

I noticed that two of the pistons have grooves on top of them. It looks like burned metal flakes have created an uneven surface on the top of pistons. The other 2 are nice and smooth. <br />Do I have a problem? Should those pistons be replaced?

 

[K Hultgre]

Re: Removing Cylinder head from 350 Mercruiser

Are the 2 pistons with problems the same two that measured low compression? Sounds like you might have some water problems (cracked head, bad exhaust manifold/elbow). Unless you can pinpoint what caused the uneven surface you might have to fight the battle again. I would take the head and have it Magnafluxed at a reputable machine shop. Small price to pay for peace of mind.<br /><br />Depending on the condition of the piston you may have to replace them. Grooves? How much difference between the bad ones and good ones, are we talking a couple of thousanths or 1/8 inch?

 

[lenny2113]

Re: Removing Cylinder head from 350 Mercruiser

Kevin,<br />The cause of low compression was blown head gasket between the 2 cylinders. <br />I pulled the head of and gave it to marina guys to send it to the shop. Grooves on pistons are very tiny but noticable. Smaller then 1/8" but still I can see it.

 

[lenny2113]

Re: Removing Cylinder head from 350 Mercruiser

Head is cracked. Does anyone know of a place where I can purchase a good quality rebuilt? <br /><br />Thanks

 

[tylerin]

Re: Removing Cylinder head from 350 Mercruiser

Lenny you said you gave it to the guy in the marina to take it to the shop, who determined it was cracked. Ask the guy in the shop. He should have a set. Or a head.

 

[K Hultgre]

Re: Removing Cylinder head from 350 Mercruiser

Do not worry about the piston grooves yet unless they are on the very edge of the piston. Any way to measure the depth of the groove? Is it in the middle of the piston?<br />The reason I inquired which two pistons was to make sure we were still talking about the same two and there was not another problem. The cracked head was leaking water/steam into the combustion chamber creating the grooves in the pistons and ultimately blowing out the head gasket. <br /><br />Dont forget to check around for the best price and warranty for a new or recond head.