Logo
FULL SITE MENU

Mercruiser 37L alpha One Head bolt pattern

R

reality4you

New member
"I have} to replace my head ga

"I have} to replace my head gasket on my Mercruiser 3.7L. Does anyone know what pattern the head bolts need to be tightened? Also, if you know the torque specifications for how tight the bolts need to be. Thank you!"
 
The torque for a GM engine is

The torque for a GM engine is 100 ft lbs. The Merc engine is 130. The pattern must be the same because the book only has one pattern listed.

Starting with the bolt under the valve cover in the center between # 2 & 3 cilinders then straight across for # 2 bolt # 3 is the bolt behind #2 #4 is straight across from # 2 between # 3 & 4 cylinder under the valve cover. # 5 is in front of # 1 bolt # 6 is straight across from 5. #7 is in the back next to # 3 # 8 across from # 7 # 9 in the front same side as # 8 last # 10. The bolts need to be taken down in three steps with the last being the final torque.
 
I contacted Mercruiser and the

I contacted Mercruiser and they told me just tighten them until there quite. Im not to sure about that answer. If anyone has a manual and they could look it up I would really apperiate it. Thanks!
 
"Just found it.

For Mark V

"Just found it.

For Mark V GM V6 and V8 engines, Tighten rocker arm shoulder bolts to 45 ft-lb. (61 N*m). Straight outta the manual.

It says for anything other than a Mark V to "adjust the valve clearance as described in this chapter"

I'm not sure what a Mark V engine is..."
 
"I have a book for 86 to 94.

"I have a book for 86 to 94. what year do you have?

a Mark V engine has studs with shoulder stops. no adjustment necessary, just torque 'em down. The hydrauics will equalize after 10 minutes or so."
 
"Russ is right, it's 20ft-

"Russ is right, it's 20ft-lb. for the rockers. The cylinder head bolts should be tightened in 3 stages 55/90/130.

A friend says that you don't HAVE to know the pattern, just start in the center and spiral outwards. I have been looking at different head bold patterns since he told me that, and it seems to hold true."
 
"My boat is a 1989. I will tr

"My boat is a 1989. I will try the 20ft-lb and see how that works. Either way after first start up I have to re-tighten the head bolts, so i have to take the valve cover off again. Thanks for all the help."
 
Back
Top