View Full Version : Head is off

07-29-2012, 08:52 PM
Took the head off today as the gasket was blown. Don't know if it looks good or bad, new territory for me.


Won't be able to tell the head guy much but is their anything specific on a tractor motor he should know?

Geo Hahn
07-29-2012, 11:54 PM
Looks like a head (IOW, I can't tell much from here).

Where did the headgasket fail? Was it between #2 and the middle coolant passage?

07-30-2012, 06:42 AM
Agree with Geo Hahn. Not much from picture. Some discoloration between 1 and 2 and perhaps carbon fouled intake valves on 1 and 4. However, IMO. the head should be disassembled, magnafluxed (checked for cracks) and checked for warpage. Also check the liner heights and be sure you don't turn the engine over (or secure the liners in place).

07-30-2012, 08:31 AM
Head is going to the shop after this to magnaflux..please be good.

Can't see where it failed. Compression check showed 165/148/130/130. Last year was 165/155/140/145. Leak down test with air pressure in #2 blew air out #3 plug hole in a big way. I'm thinking the cause of gradually increasing overheating problem.

I have been careful not to turn the engine. Book says liner protrusion should be .003"-.005". Number one is less than that. #4 is .009". Should I try to pull it down with washers on the studs or some other way or is it likely to stay put?

Geo Hahn
07-30-2012, 08:40 AM
I use a couple of big washers, long sockets and head nuts to assure the liner don't lift when the enigne is turned. I also put a couple of pieces of cardboard over the cavities for the push-rods in case I drop something.


Can't comment on whether you should mess with the liner protrusions -- how much less than spec are the low ones?

07-30-2012, 08:49 AM
I how much less than spec are the low ones?

Smaller than my gauge. You can just feel them with your finger and defiantly catch a finger nail on the edge. Is that close enough for British precision?

07-30-2012, 11:09 AM
I would reckon the head gasket sealed the oil and water from mixing so the protrusion should be ok. To fix that is a bigger job. You would at least need to replace the figure 8 gasket and depending on how stuck and rusted the liners are will make the job more difficult and thatís after you pulled the pistons. The air leak test is not something I am familiar with, but something does not sound right. Anyways, I would ask the machine about a valve seat problem and that could fix the air leak deal. After that and depending on what they say, I would purchase a top of line head gasket, put that on, and leave the liners and see if it seals just because you might as well do a rebuild if you pull the liners.

07-30-2012, 04:12 PM
Looks like the head will have to be surfaced, at the least. Here is a blowup of the area that I think is a problem.

Liner protrusion seems fairly critical to me; I fought head gasket problems for many years before finally figuring out that it wasn't enough only on one side. The mixture of less than .003" and .009" would also seem to be a problem to me. I might put it back together that way once, but if the gasket blows a second time then for sure I would try to get the protrusion right across the board.

That said, this band-aid has been working well for me for many years now (ever since I figured out that not enough protrusion was a problem).


07-30-2012, 06:04 PM
Thanks all. Geo, did your set up. Head is in shop for clean and check. Once done with what sp53 let me know sounds like can't change things so put it back together and hope for the best, otherwise engine comes apart. Since the low liners have the best compression I will skip your improvisation Randall. I am also going to skip replacing the front cover gasket just in case. Waiting for head guy to call now.

07-30-2012, 07:03 PM
Might be less attractive with a TR4A, but it is definitely possible to pull the liners with the engine still in the car. I've done it on my TR3A (mostly to avoid having to remove the front apron) and I wasn't sorry later. Kind of unpleasant to work looking up into the engine but otherwise no harder than doing it on a stand.
To drive the liners out, I made up a "drift" from a length of water pipe and a brass cap (to avoid chipping the edge of the liner). It has worked well on every liner I've tackled, except for a couple of engine blocks that were left outside in the rain for many years. They likely won't come apart short of breaking the pistons & liners.

The "fire rings" don't affect compression enough to matter. The wire is only .020" or so, and most of that gets either mashed flat or driven into the gasket. The main point is to get some extra "crush" around the cylinders, where the pressure is highest. Very similar to a trick used by many racers on supercharged engines, when the pressure is so high that head gaskets blow out (which is where I got the idea from).

07-30-2012, 07:44 PM
Well maybe I'll get out my soldering gun tomorrow since I have a gasket set from TRF. As for the drift idea, I'll get back to you.

And while I wait, what about putting an equal amount of fluid in each cylinder and watch leak down. At this point I probably wouldn't do anything about it but is that a good check for rings?

Geo Hahn
07-30-2012, 08:37 PM
I suspect fluid just sitting in the cylinders will go nowhere unless the rings are broken. A compresison test (wet & dry) is usually the best way to check the rings.

Though replacing the rings at this point is a walk in the park compared to Randall's task of pounding out the liner from under the car. Of course if you do the rings then you'll also want to do the big end bearings... and so it begins.

07-30-2012, 11:35 PM
Of course if you do the rings then you'll also want to do the big end bearings... and so it begins.
One of the few things that I always plan on replacing, any time they are removed. Another long term consumable.

07-31-2012, 05:42 AM
Of course if you do the rings then you'll also want to do the big end bearings... and so it begins.
One of the few things that I always plan on replacing, any time they are removed. Another long term consumable.


07-31-2012, 06:09 AM
dont know much about the liner issue, just have the head checked, boiled out. have the valves and seats ground, resurfaced, new gasket and put it back together, otherwise you will be replacing liners, pistons, rings, bearings, yada yada, thats how is starts


07-31-2012, 09:18 AM
Have not used them, but I recall hearing that the Cometic composite gasket may seal better - but unfortunately they are pricey. The potrusion is worrisome but I'd try the gasket / head surface first. And I'd pull the engine before the liners came out - too much gunk to deal with around 3 and 4 cylinders typically.