Three cylinder ford 4000 valve cover, nuts and washers

This may seem to be simple and obvious, but I need to know.

The 1973 Ford 4000 I am working on has leaks around the valve cover. I had to take the cover off anyway and clean out years of accumulated varnish etc. After I cleaned it I checked the rim for flatness and had to spend an hour carefully leveling the mating surface.

I think part of the problem was the 8 nuts were over tightened, but the washers on this cover were lock washers which would tend to distort the thin metal. Does anyone have a picture or description of the type nuts and washers used for these? I searched the internet and cannot find a picture or list of the correct fasteners. I like to keep things original where I can.
 
Bob,

Thanks. I don't know why I said nut when I should have said bolt.
I did not think to go to the New Holland parts site. I guess I am used to seeing "no longer serviced or obsolete" When looking for Dexta parts.

Well it looks like someone replaced the flange bolts with regular hex head bolts and lock washers----not good. This will definitely affect the sealing ability. Even a new gasket would not seal very well.
 

I know the parts lookup says flange bolt but I have four -000 series tractors and none of them have flange head bolts holding the valve covers, also my 1990 parts manual doesn't say flange bolt.
I believe Ford switched to flange head bolts on later model tractors and updated the parts books to the newer bolts
Their also not fine thread - NF.

The original bolts do have a thick lock type washer on them. A easy way to tell if they are the correct ones is the lock washer will not come off of the original bolts, if you can remove the lock washer the originals have been replaced.

This has got my curiosity up, I have a 97 model 3930 engine setting in the shop, I'm going to look to see what bolts it has.

If the valve cove flange is bent, someone has over tightened the bolts, happens all the time.
 
Destroked 450,

Thanks for the additional input. The lock washers do come off of these bolts so they were not original.
I can understand why Ford changed these. The flange bolts are less likely to distort the rocker cover while the required torque to flatten a lock washer (aka split washer) might vary.

Your post made me look up "How do lock washers work?" and I found an interesting article on work done in the late 60s by Gerhard Junker who did some research and found that split washers loosen sooner due to transverse loading. Maybe this is one of the reasons Ford switched to flange head bolts. The timing of this makes it a reasonable possibility in my opinion.

While you are checking on that 3930 could you look to see if the flange heads are smooth underneath or serrated. The New Holland site does say grade 5, but the part number does not say smooth or serrated.
 

Finally got back in the shop and uncovered the 3930 engine enough the look at the bolts, had a lot of stuff piled on top of it.
The bolts are flange head with what looks like 10mm heads, didn't take one out to see if it was serrated or not.
 
Speaking of cool lockwasher designs, came across some aftermarket motorcycle ones that go on as a pair - two reverse ramps with interlocking serrations, bottom face ends up perpendicular to bolt so you get a great clamping surface..... Can't remember the brand name though.
 

In general terms, a bolt will not loosen when the clamping load exceeds the load the bolt sees in operation. In this case; there is [u:1ef5c55242]no movement[/u:1ef5c55242] between the parts and the bolt does not back out. This is why for example, connecting rod bolts do not use lock washers and the bolt does not loosen.

A valve cover does not see large loads in operation. Therefore, the bolts do not need to be highly torqued to remain tight. If it were me, I would replace the bolts with flange head bolts and get on with it. Be sure to torque all equally, so that all the bolts see the gasket load.

Note, other way to look at this is the gasket becomes the lock washer as it maintains load on the bolts.
 
Indiana Ken,

If I understand Gehard Yunker's work transverse loading can also loosen bolts. This can come in the form of engine vibrations, but I think in this case leaks from the rocker cover came from bolt over tightening and hardening of the gasket with a corresponding loss of compressive strength.

I have also seen leaks occur when changing to an oil which had higher penetrating properties (if that is the right term). It was not in a tractor, but the Pennzoil 5W30 Platinum I put in our car found very small fissures in the rocker gasket and caused leaks. The previous oils I used were also synthetic, but did not do this.
 

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