45 head gasket

[RvP]

I think my head gaskets are leaking after 3 years. There is oil residue on the rear of the rear head and on the front of the front head. I used the Teflon coated gaskets, torqued them when I put them on and re-torqued them 100 miles later (cold). Just wondering what is the best head gasket material to use, Teflon ,asbestos or copper? I am using #5 aluminum heads and I would like to try copper head gaskets but I have a faint memory reading somewhere that you should not use copper with aluminum heads, only cast iron heads. Is my memory correct and what is the recommendation from the membership?

[oldsouthmcy]

Speaking strictly about gaskets from the factory's original point of view. The only difference between the 11-36 (1936-1950 iron head) and the original 11-39 (1939-1950 aluminum head and 1951-1957 45 models) was the hole size. 11-36 was for the 3/8" cylinder studs and 11-39 was for the 7/16" cylinder bolt. Both gaskets, 11-36 & 11-39, were originally copper.

In mid-1942, the gasket material for the aluminum head models was switched to asbestos to conserve the use of copper. Not having looked at many 11-36 gaskets, I cannot say positively if they were also converted. The US Army did not worry about the change but the Canadian military did. Canada was concerned that the thicker material would adversely effect the performance of their WLCs. To assure Canada that the asbestos gaskets' thickness was negligible to the performance, testing was done in September 1942. The results proved without doubt that the thicker material was safe to use.

Back to your concern, the copper gasket will not harm your aluminum head.

As to your leakage, before installing a new gasket of any material, make sure that your head and cylinder surfaces are level and not warped.

I like to use silver paint on both sides of a head gasket to allow the gasket to creep when tightening. Be sure to tighten your heads using the criss-cross pattern. Tight is 60 to 65 foot pounds when using the 7/16" bolts.

[RvP]

Wow, great information! That cleared up the old wives tales I heard about the using a copper gasket with the aluminum head which does not allow for the expansion between the steel cylinder and the aluminum head as good as asbestos or Teflon does.

I have not checked if my copper head gaskets have the correct hole size in them or not yet, I have to dig them out. I also bought a can of copper spray gasket to spray the copper gasket with when I am ready to do this on the next oil change.

I did take my 45 to an event where one of my fellow club members that has been running 45s for years would be to take a look at my oil seepage. He felt from the pattern the oil was most likely coming from under the head bolts and not between the head and cylinder. He said this was a pretty common point of failure with the head gasket since the gasket has little material around the bolts. If he is correct this alleviated my concerns about the combustion escaping at the head/cylinder joint and melting the head in that area.

Since the engine seems to be running strong, i.e. starts easy hot or cold, idles decently and has a good top end, next oil change would be an opportune time to remove the tanks and do the head gaskets.

I will also check for warpage on the head and cylinder with a metal straight edge and slightly hone the head on a sheet of glass with very, very fine grit sandpaper.

One more question, what the best way to remove carbon from the head, piston and valve area besides carefully scraping with a dull wooden stick?

Thanks again

Ronald V. Papasso

[Rubone]

One more question, what the best way to remove carbon from the head, piston and valve area besides carefully scraping with a dull wooden stick

Use a sharp wooden stick!
Robbie

[RvP]

I learned a lot over the last week……

First thing is not all #5 aluminum heads are created equal. When I pulled the heads I found there were areas that it appeared the gasket was not compressed. Since I used a torque wrench when I put the heads on and checked the torque before puling the heads this was a puzzle.

Then I found on line a military technical manual, no. 9-879 dated October 18, 1943, that stated the #5 aluminum heads are not milled to the same height where the head bolts pass through. Some are 31/32” and others are 1 1/16”. The manual states to use a 0.095” washer in addition to the heavy cylinder head bolt washers to prevent the head bolts from bottoming with the heads that are 31/32” where the head bolts go.

I measured my #5 heads and they both were 31/32” thick where the head bolts pass through. I then made a gauge the thickness of the head were the bolts pass through and inserted all the head bolts plus heavy washer into the cylinders without the heads. Using the gauge I found some of head bolts were slightly taller then the gauge. This meant those bolts would bottom before the head would be properly torqued.

Looking at the tapped holes in the cylinder some places have more “meat” than others and the holes were drilled deeper. Where the head bolts would bottom before tightening the head the tapped cylinder holes were not as deep. To remedy this I bought steel washers close to the same diameter as the heavy washers and placed them under the heavy washers. I only did this where the head bolts were bottoming because I was concerned about not having enough thread and the threads stripping when torqued.

Next thing I learned is Teflon does stick to aluminum and steel. When I pulled the heads the Teflon was melted to the head and barrel with the metal gasket floating free. It was extremely difficult and time consuming to remove the melted Teflon from the head and barrel. Maybe this happened because the head was not tight which allowed the combustion to escape melting the Teflon. It was very time consuming to shave the melted Teflon off with a razor blade.

The copper head gaskets I had did not have to be modified. The holes where the head bolts pass through were slightly larger in diameter than the head bolts. I sprayed the copper gasket with copper gasket spray (both sides) and put them on. Since doing this I put on 120 miles and there are no head bolt leaks spraying oil on the rear fender or generator.

Thanks again for the advice and help

[foxman86]

if u take the coper gasket and use a hevey dudy industral paint and dip the geasket in let dry till its still a little stiky then bolt the head on the jug it will seal nicely.