Mercruiser 898 headgaskets...

[thrttlebkhtrod]

I purchased a 1980 Glastron/Carlson cvz-18 from a gentleman (aka dooshbag) The boat was unwinterized, oil changed and i ran the boat with the guy, went over some things and struck a deal. Well after a month of sitting, yesterday i started and ran the boat for 30min, boat ran beautiful. I check the oil and the oil was slightly milky. I pulled the intake, no cracks present, the motor actually looked brand new possible replacement at some point.. Also no water in any cylinders.
Anyway i did a leak down test and found cyl# 8 to be leaking.... I have a couple of questions

1- How different are marine gasket kits from automotive gasket kits (if any)?

2- Does anyone know the torque specs/sequence for the heads?

Any input is appreciated guys

 

[cr2k]

Re: Mercruiser 898 headgaskets...

Marine headgaskets use stainless instead of steel. Torque is either 65 or 80 fp I believe. Hope someone helps here. Spiral out from the center.

 

[thrttlebkhtrod]

Re: Mercruiser 898 headgaskets...

Thamks cr2k.....Yes i did a tad more research on the gaskets and im just going marine gasket set.. Can anyone else put some input in on the torque specs/sequence?

 

[joewithaboat]

Re: Mercruiser 898 headgaskets...

Thamks cr2k.....Yes i did a tad more research on the gaskets and im just going marine gasket set.. Can anyone else put some input in on the torque specs/sequence?

Going to need some more info on your engine (serial number) before folks will give you torque specs. That's if you use an oem type of gasket. Me personally, I would use Felpro with a stainless ring. They come with their own set of torque specs. Make sure to use sealer on the heads bolt threads. Some require a re-torque after initial run to operating temp.

A wild guess that it is a small block Chevy, if so this is the marine felpro

Fel-Pro Q17030.... sold each... perma-torque, no re torque necessary!

http://www.summitracing.com/parts/FEL-17030/

 

[thrttlebkhtrod]

Re: Mercruiser 898 headgaskets...

I purchased a head gasket set from my local marina who is an authorized mercruiser servicer. So im assuming its a factory gasket set. Also why do i need to seal the threads on the head bolts? Ive built a few engines in the past and never sealed the threads.. also ive only re-torqued stretch bolts, these are not stretch bolts. Ill grab the serial# but arent all gm 305/350 heads/blocks the same? I know some torque specs are by gasket type...

 

[achris]

Re: Mercruiser 898 headgaskets...

I purchased a head gasket set from my local marina who is an authorized mercruiser servicer. So im assuming its a factory gasket set. Also why do i need to seal the threads on the head bolts?

Because the bolt holes are open into the water jacket... If you don't use sealer on the threads water will track up the threads and into the oil...

Ive built a few engines in the past and never sealed the threads.. also ive only re-torqued stretch bolts, these are not stretch bolts. Ill grab the serial# but arent all gm 305/350 heads/blocks the same? I know some torque specs are by gasket type...

898 was only from 1977 to 1985, so I checked and all 898 engines have the same head bolt torque, 65lb.ft.... Torque in steps. And warm the engine and re-torque while warm... Here's the sequence.

 

[thrttlebkhtrod]

Re: Mercruiser 898 headgaskets...

You my friend are the man... So do i use any type of sealer? black gasket type silcone ok? Is the sequence on the bottom of the picture the other side?

 

[achris]

Re: Mercruiser 898 headgaskets...

Run a tap down each bolt hole to clean it up, then on stainless steel gasket use a thin smear of sealer (NOT silicone, use something like Permatex). On composite gaskets, put on dry. Put sealer on the bolt threads... The picture below the main one is the thumbnail for the main picture, they are the same. Torque sequence is the same for both sides.

 

[thrttlebkhtrod]

Re: Mercruiser 898 headgaskets...

I will do that.. i ment the eight bolts going straight across the bottom of the picture, sorry about that..just a tad confused on those

 

[achris]

Re: Mercruiser 898 headgaskets...

No, that's one head... 16 bolts in each head...

 

[thrttlebkhtrod]

Re: Mercruiser 898 headgaskets...

Well that explains it.. I have some permatex cooper gasket stuff thats good for 700 degrees. I appreicate you taking the time to help. Thanks a bunch. I also made from a old distributor a pump that i hook up to a drill to remove all the oil in the motor using the oil pump, ill pump it through the oil pressure output. Im hoping it will save some time with flushing the motor