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Old 03-24-2012, 10:05 PM
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Default head gasket questions?

Hi all,

I have a lateish '74 '40 (F155 engine), that I realized was leaking coolant into the front cylinder (number 1 I believe, but not 100% certain). I learned becuase i was trying to put in a big cover dizzy & dented side cover & pulled that plug to find TDC, and had water squirt out when I bumped it over.

so I pulled the head a little while earlier, and I can't find any specific damage to the Head Gasket, but I've bot some questions.

1. I thought they were usually a metal base, with some sort of layer over them. But when I cleaned it up, it seems to only be a metal sheet. Is that correct?
2. Is it possible to leak through the gasket without any visible signs of it being blown out?
3. There seems to be some rust or somethign inside the cylinder. I haven't tried to clean it really well yet, other than wipe it down, as it was getting dark. But how much is too much, and what is the best way to clean it, to tell if it is okay?
4. What's the very cheapest way to get this truck running again? I don't have a lot of spare cash right now if you know what I mean...

I took some pics, that I will download & post, in case they help. But I don't know if they will provide any insight.
THanks in advance!
Best,
Abe
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Old 03-24-2012, 10:21 PM
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Default Pics of the block/gasket/head

Name:  Cylinder wall.JPG
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Name:  Cylinder wall #2.JPG
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Size:  133.6 KB

Name:  Head Gasket.JPG
Views: 148
Size:  107.1 KB

Name:  valve & head.JPG
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Name:  Valve & Head #2.JPG
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Size:  90.0 KB
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  #3  
Old 03-25-2012, 07:26 AM
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I'd take some Scotchbrite to the rust and polish away. If the rust comes off, great. If the rust has eaten into the wall of the cyl, you could either leave it or spend a bunch of money to get rid of it. If the the rest of the engine is original with lots of miles, just clean up the corrosion and call it good.

Inspect both the head and block for cracks or bumps that might effect the sealing of the head gasket. Inspect the head gasket with a magnifying glass to try to see the path of the coolant to the cyl. Inspect the combustion seal flange on the gasket for cracks. If you can't find any evidence of the leak or reasons for the leak, Put a new gasket on it and put it back together.

Did any of the headbolts seem to be a lot more loose when you took it apart? It may have leaked due to loose or improperly torqued bolts. Maybe it overheated? That can cause the gasket to be crushed and loose sealing stress.

The picture of the gasket looks like normal gasket construction - a perforated steel sheet with paper on both sides and a steel combustion seal. There are steel shim gaskets without paper out there but I doubt one is made for the 2F. They are usually higher cost designs for engines that are more difficult to seal.
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Old 03-25-2012, 08:20 AM
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It's best to chase the head bolt holes with a tap before reassembly.
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Old 03-25-2012, 09:25 AM
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How many miles does that engine have on it? I would seriously consider taking the head in to a machine shop and having them check it for cracks, not an uncommon problem on F/2F heads. If it has no cracks then they can check to make sure it isn't warped and they can deck it to ensure it is flat. Once you have cleaned the block surface really good, then check it with a steel straight edge too to make sure it is flat as well. If it has enough miles on it, you may want to have them do a valve job on the head to ensure the seats and guides are all good. Overall not that expensive to do. While the head is off, you should also drill out the oil galley plug, tap it then put in a threaded plug. That could save your engine later.

You can clean that cylinder up with some steel wool, then run a hone in it with the piston at BDC. It should be fine as these old tractor motors never ran very tight tolerances even when new.

Too bad you didn't run a compression check on it before you pulled the head. If a few of the cyliners were down on compression it's super easy at this point to drop the oil pan and put some new piston rings in it too.
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Old 03-25-2012, 09:49 AM
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Thanks for the ideas guys!

The head gasket itself doesn't have any paper on it now. Is it possible I, "scrubbed" it off when I hit it with the pressur washer @ the coin op place?

I have no idea how many miles the engine has, but I would guess a lot. I bought it cheap, having sat for years, and only drove it for about 20 miles before I broke the distributor trying to figure out why it seemed like it wasn't advancing/retarding under power. But it never ran well in the time I had it running. It has seen a lot of neglect, but mostly from sitting, rather than harsh use.

When I say, "cheapest" way to fix, I actually meant that I don't have thousands of dollars to take it somewhere for a rebuild. Since the head is off, & I don't know much about it, I was going to take it down to Gunn Automotive this week & have them clean it & magnaflux, etc... Am I wrong to assume that they will do the valves on all if i tell them to, "rebuild" the head, or do I need to specify that sort of stuff?

When the time comes, does anyone in the Boulder area have a Tap I could borrow for the head bolt holes & maybe also the Oil Galley Plug?

Randy - I assume that the rings are mediocre at the best, just based on how neglected everything is, but that is only a guess. I like the idea of new rings & fresh new compression, but pulling the head pretty much extends beyond my ability level, so the rings are not likely. Although I have been reading RcardoJM's f.5 rebuild thread, and the ring compressor doesn't look horribly complicated.

I'll go clean it up further & see what it looks like, now that it is light out & warming up. I'll let you guys know what it looks like when I get it cleaner.

Thanks!
Abe
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Old 03-26-2012, 01:24 PM
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Quote:
Originally Posted by subzali View Post
It's best to chase the head bolt holes with a tap before reassembly.
When I was picking up my block at the machine shop the other day they apologized for not chasing the head bolt threads, explaining that they are an oddball 17mm pitch and they do not own a tap that size.

If an engine shop doesn't have one, they are probably pretty hard to find, and likely pretty darn expensive...
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Old 03-26-2012, 01:30 PM
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Abe, I would certainly check the head for flatness. While the F heads are not nearly as prone to cracking as the later 2F heads, it is certainly possible. I tend to agree with Bruce, clean it up as best you can then do as much inspection as you can, try to find to cause of the leak. If you can't find the cause, you could be wasting a lot of time by not fixing the right thing.

I like to use a wirewheel on an air powered die grinder to clean up rust, carbon and old bits of gasket. You can also use an electric drill but it takes longer. Scotchbright by hand takes even longer still. Whatever you do, make sure you plug off the holes where the pushrods go so you don't get too much crud down in the oil.
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Old 03-26-2012, 01:49 PM
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Quote:
Originally Posted by gr8fulabe View Post
Thanks for the ideas guys!

The head gasket itself doesn't have any paper on it now. Is it possible I, "scrubbed" it off when I hit it with the pressur washer @ the coin op place?

I have no idea how many miles the engine has, but I would guess a lot. I bought it cheap, having sat for years, and only drove it for about 20 miles before I broke the distributor trying to figure out why it seemed like it wasn't advancing/retarding under power. But it never ran well in the time I had it running. It has seen a lot of neglect, but mostly from sitting, rather than harsh use.

When I say, "cheapest" way to fix, I actually meant that I don't have thousands of dollars to take it somewhere for a rebuild. Since the head is off, & I don't know much about it, I was going to take it down to Gunn Automotive this week & have them clean it & magnaflux, etc... Am I wrong to assume that they will do the valves on all if i tell them to, "rebuild" the head, or do I need to specify that sort of stuff?

When the time comes, does anyone in the Boulder area have a Tap I could borrow for the head bolt holes & maybe also the Oil Galley Plug?

Randy - I assume that the rings are mediocre at the best, just based on how neglected everything is, but that is only a guess. I like the idea of new rings & fresh new compression, but pulling the head pretty much extends beyond my ability level, so the rings are not likely. Although I have been reading RcardoJM's f.5 rebuild thread, and the ring compressor doesn't look horribly complicated.

I'll go clean it up further & see what it looks like, now that it is light out & warming up. I'll let you guys know what it looks like when I get it cleaner.

Thanks!
Abe
If you tell Gunn to rebuild the head they will check it for cracks first, then do the valves and resurface it to ensure it is flat. If you ask them, they will also do the oil galley plug for like $5.

Now that you have the head and valves off, you've done all the really hard stuff. If you want to install new rings just drop the oil pan. Take one connecting rod cap off and push the piston up and out of the cylinder. Rent a cylinder hone at one of the parts stores, hone the cylinder, install the new rings on the piston, compress them (another rental tool), squit some oil in the cylinder and gently insert the piston. Put the new bearings on the connecting rod, bolt and torque the cap, now do the other 5 pistons one at a time. Just make sure you put the piston back in facing the same direction it came out. Very easy to do. Not as good a true full rebuild but will add some life to the motor for very little money.

A lot of times when you do a valve job on an old engine (where the valves may not have been sealing perfectly for some time) you raise the compression in the cylinder. That can make the old piston rings die quickly if they are close to the end anyways. Thus the logic for sticking a set of rings in as a safety measure.
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Old 03-26-2012, 03:19 PM
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Quote:
Originally Posted by Rzeppa View Post
When I was picking up my block at the machine shop the other day they apologized for not chasing the head bolt threads, explaining that they are an oddball 17mm pitch and they do not own a tap that size.

If an engine shop doesn't have one, they are probably pretty hard to find, and likely pretty darn expensive...
I think you're right

I didn't chase mine and it seems to be fine. I also didn't replace the rings and they seem to be ok for now. Gunn will lap the valves and if any need to be replaced they will tell you. I think one of mine needed to be replaced, and they replaced all of my springs too.
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