Do I need to mill the block??

[boredindaboro]

I have an 88spl that had a head gasket leak. I know it was over heated. I plan on having the heads square after deciding against the table and sand paper method. Had anyone used the sand paper method? If so can you give details? Lastly do I need to have the block decked? Never worked on this type of engine before. Thanks

 

[HenryB]

If you have a local machine shop they should machine the heads flat and good as new for short money. The block is different story. Do not understand "decked".

Examine the block for grooves across the gasket surface. Grooves mean big money. No grooves mean no money.

 

[Bosunsmate]

This guy does it on this page
http://www.maxrules.com/fixtuneitup2.html

Just use very fine sandpaper for the finish,
not sure about decking too.
Check your crankcase is flat first, a warp theres bigger trouble

 

[emdsapmgr]

A machine shop can measure the flatness of the head surface(s) in order to determine if the block needs to be decked. It would be fairly unusual if either block face would need to be decked. If either was out of flat, you'd probably have other issues with the block-you'd better check the crank journal surfaces for bore alignment also. Is there a lot of paint bubbling off the block from the overheat?

 

[racerone]

These heads all warp ! --Even on motors that have not overheated.----The factory manual say that it can be corrected with paper and a piece of glass.-----I have done many of them that way with no issues at all. !!-----When heads are flat you can use them to check the block.------I use a piece of news paper and if it grips that you are good to go.

 

[pro-crastinator]

"decking" refers to the process of leveling the gasket surface on the block - where it comes into contact with the head.
I think that large, heavy, complicated special tools are involved - that clean up large surfaces consistently - like a bank on a v8 engine.

 

[F_R]

The block probably is out of flat some. But lucky, they are fairly forgiving if the heads are perfectly flat you can probably get by. To machine the block would require removing the powerhead and some disassembly.

 

[boredindaboro]

How do you ensure the sandpaper is level and smooth to the glass? I would be happy to try it but I would love more detail in how you ensure the sandpaper is as flat as the glass. Not dumb just poor and don't want to cost myself more cash trying to be cheap.

 

[F_R]

The purpose in using glass (or another very flat surface like a machine tool table) is the sandpaper will lay flat against it when under the weight of the part being dressed. It is the method suggested in most service manuals, not something we've dreamed up.

BTW, be careful with that glass. Plate glass or tempered glass is preferred. Window glass can shatter and cause serious cuts when it does (ask me how I know).

 

[Tim Frank]

Just use very fine sandpaper for the finish,

Correct.....to a point.
You need some "tooth" to seat the gasket, if you go too fine you may not get as good a seal.
Anything finer than 400x is overkill and may be counter productive.

I use a granite surface plate with wet/dry SiC paper. Start at 120x move to 240x then finish with 400x

 

[boredindaboro]

What do you secure the sand paper to the glass with? I Am afraid the adhesive would leave ridges in the paper and the head? I guess that is my greatest fear.. could someone describe their method so I don't screw it up? Thank you

 

[racerone]

Why not use some valve grinding compound on a piece of glass.-----After you are done you will be proud of your work and say " that was easy "

 

[pro-crastinator]

Pick up a can of spray adhesive, spray glass(or other flat portable surface), affix sandpaper, rub on heads surface, hope for the best outcome.

 

[Tim Frank]

It is the relatively small size of an outboard head that allows this. An 8 cylinder head is a different animal....
This method has always worked for me:
1) With a known-good straight edge, check across the head in various directions to see how "bad" it is. If there are more than ~ 0.010" gaps, it is probably a machine shop job, or get a new or replacement head.
2) Glass will work...edge-tape or spray adhesive will hold the abrasive sheet....or use lapping grit/valve grinding paste.
3) Hold the head and move it ON the lapping surface,which should be on a stable flat surface itself...not vice versa.
4) Use a gentle, circular motion....small radius is best....the weight of the head is all the pressure needed. Too much pressure is counter productive.
5) You will quickly see the emerging pattern of progress, with the high spots clearly showing until you get them leveled.
6) Start with 120X, when you have just removed the last "valley", switch to 240X to refine the surface finish, and finish with a 400X.

IMO, point # 4) is the most critical.

 

[HenryB]

Call local machine shop for quote. It might not be as much as you think to dress out both heads.

 

[boredindaboro]

So i ask going to straight edge the heads and see how bad they are. one is not leaking but I can promise you the water deflectors are shot so I Am changing both. What is the torque specs for the head bolts and what do I put on them? Should I use anti seize or is there something else I need to coat them with? Thank you again

 

[Bosunsmate]

i dont know the head torque specs but i give all the bolts and the threads in the crank case a clean and then i put a fine coat of oil on the bolts.
Some people use anti seize.
You also need to torque in a pattern from the centre out in a circular movement, so you finish with the top two then the bottom two.
Do that in two stages and then retorque after you have given it its first start up and warm up

 

[Bosunsmate]

By the way you would be able to find the torque range in here
http://boatinfo.no/lib/library.html
its probably around 22 ft pounds
Above- retorque after its cooled

 

[emdsapmgr]

1990 factory service manual V4 head bolt torque: 18-20lbs. Performed in stages. Circular sequence starting from the center of the head outward.

 

[boredindaboro]

Thank you for the torque info. I resurfaced the head today, will finish tomorrow with a pass on 320 grit. Worked great! The plan is to see if once assembled, do I have good compression out of the low cylinder, if so, then I will do the other the water deflectors in this side were shot.. Does anyone have a pic or video of the proper placement of the deflectors? Wanna make sure they are right before I torque the head. Thank you all again!!