TR4/4A Question on re-torquing the head if it has leaked

[tdskip]

Hi guys - doing some research on my TR4a coolant issue (blown out the overflow) and wondering if you an re-torque a head gasket in place if it has leaked or if that is an automatic replace it event?

 

[Rubicon]

You can try a retorque, but if you find all the bolts up to torque, likely it's not gonna help and you'll need a new gasket. But it's a cheep and easy try to see if it fixes it.

 

[TR3driver]

IMO it's an automatic replace. Plus while it's apart, spend some time checking for why it started leaking in the first place. They don't just blow for no reason; something went wrong. I'm sure I've mentioned liner height (on all sides) before.

Another place to check carefully is for distortion in the stud threads. Make sure they are clean (steel wool or similar, NOT a thread chaser or threading die) and spin a new nut down the threads by hand. If it doesn't spin easily all the way, binds about 2/3 down, chances are that stud is distorted and must be replaced.

And obviously, check the head to be sure it's flat. .001" or .002" in a gentle curve is probably OK (it will distort that much when clamped down), but any more than that (or any scrapes or gouges) is cause for a visit to the machine shop to have it skimmed.

Check around the short stud holes, to be sure the block surface is not raised. My preference is to remove the stud, lay down a flat machinists file (no handle) and lightly rub it along the surface. If the surface is flat, the file won't bite and the teeth will just slide. But if there is a raised area, the file will bite and show you the high spot.

 

[CJD]

Ditto...it needs to be replaced.

 

[tdskip]

Ok - off the head comes.

Thanks.

 

[charleyf]

One more area of potential failure is the gasket itself. These gaskets look like they can be put on the block either side up. But my sad experience is that the gasket needs to have the seams oriented up toward the head and the solid (without seams )on the bottom. On my car the seam was put down and the water passage at the rear of the motor was able to attack the gasket and breach the gasket, dumping coolant into the rear of that cylinder. On a second engine I found water stains in the same location on number four cylinder. I do't know the cause just that it happened not to long before I bought the car. PO of course said nothing, but decided to remedy it with a solid copper gasket.
Charley

 

[tdskip]

Thanks guys.

Will start pulling the head today.

 

[TR3driver]

One more area of potential failure is the gasket itself. These gaskets look like they can be put on the block either side up.

There's actually a service note somewhere to the effect that the gasket was modified to allow installation either way up. (An extra oil hole was added, so the rocker feed won't get blocked.) However I also like to install it with the seams up.

 

[charleyf]

When one looks at the water passages in the head at the rear of the number four cylinder ( rather small) and the water passages in the block at the same location ( rather large), it is easy to see why the gasket creates a weak spot.
Charley

 

[tdskip]

Hi guys - obviously not making fast progress on this.

The head is really stuck on the there - tired PBlaster on the head studs to see if that would help but no dice. Anyway I can use a engine picker (lift) to help get it out rather than resorting to the rope trick?

Thanks, and hope everyone is off to a good start of their weekend.

 

[Geo Hahn]

I have not been in that position but wonder if a steady pull with an engine hoist will be effective - all you're working against is the weight of the car. Worth a try I suppose.

Have you tried simply cranking the engine (with the plugs back in) to see if compression is able to move it? Any movement at all and you've won as that would allow wooden wedges and such to go to work.

On Jaguar XK engines it is common practice to use a bottle jack to move the head up - but off hand cannot picture where it would sit on a TR engine (Jaguars have a lip that is practically made-to-order for that).

 

[tdskip]

Hi Geo - thanks for the note back.

I did crank her over with the plugs in, but no dice. Let me try a wooden wedge again with some anger this time

 

[TR3driver]

I've tried pulling a head with the engine hoist. Didn't work for me, even though the head wasn't particularly stuck. After lifting the entire car that way, I set it down and lifted the head off by hand.

My guess, it was binding on the studs.

On the Stag (which has severe problems with stuck heads due to its hybrid aluminum/iron construction), some clever fellows came up with a puller that bolts to the head on both sides, and has forcing screws for each stud. Might be able to build something similar for the TR motor, tho I'm not sure offhand where to attach on the push rod side.

Another extreme approach (which I may attempt on my Stag) is to build a simple EDM (electrical discharge machining) machine that can be used to cut the studs out of the head. I've seen plans published in Home Shop Machinist that look pretty easy to duplicate. Just a rectifier and resistor for the power supply, and a simple circuit to run a stepper motor one direction when the voltage is too high (no spark) and the other direction once the spark starts (low voltage). The cutting tool is just hollow brass tubing, plus a small pump to circulate fluid through the center (to carry away the dust).

 

[tdskip]

Another extreme approach (which I may attempt on my Stag) is to build a simple EDM (electrical discharge machining) machine that can be used to cut the studs out of the head. I've seen plans published in Home Shop Machinist that look pretty easy to duplicate. Just a rectifier and resistor for the power supply, and a simple circuit to run a stepper motor one direction when the voltage is too high (no spark) and the other direction once the spark starts (low voltage). The cutting tool is just hollow brass tubing, plus a small pump to circulate fluid through the center (to carry away the dust).

Sounds like a good excuse to fabricate something! More specifically, a good excuse for you to fabricate something since I'd blow the house up trying that.

 

[TR3driver]

I forgot to mention, the "resistor" can be just an ordinary incandescent light bulb. So in effect, the electrode and work piece become a switch that turns the light on and off very rapidly, drawing a tiny spark each time it turns off. Obviously a very slow process, but since the worst that can go wrong is the light bulb stays on; it can be left to work for as long as it takes.

I've done far worse things. One year in college, I made a Jacob's Ladder that we let run in the apartment until we got tired of the smell & noise.
https://www.youtube.com/watch?v=vOYy5NZ4hWA

 

[TomMull]

I am intrigued by the EDM ideas but they are a bit beyond my meager electrical experience. I have, however, had considerable success with Neanderthal tactics, that I know are forbidden, but that worked for me with no damage. I have a beefed up scraper with a sharp edge that I use for breaking spot welds, that I jammed into the head gasket seam and tapped with my favorite two pounder.
Tom

 

[tdskip]

Hi Tom - that is more my speed / skill level :wink-new:

 

[sp53]

Yes those heads are really stuck most times. I too feel more comfortable with a caveman approach. After a 4 year apprenticeship I became a journeyman carpenter in 1982 and that is after working non-union many years before that, so I got a good education on big hammers and wedges. I would just add to the caveman approach to be careful where to start the wedge. When I visualize the engine block, that area by the lifters looks fragile for cast iron. In the past I have noticed the head is often stuck on the head studs themselves, and some are bent. Plus having 10 heads is binding anyway, but pulling those head studs out can crack the block also.

What I do is squirt WD40 in all the stud holes and then put a nut on the stud and tap the nut with a 20 once hammer and listen if I can hear ringing and vibration to see that it is free from the head on the stud shank. I have also pulled the shorter studs out of the head with a double nut if they come easy. I figured the short one might not be bent, but it might let some pressure off the long ones. The long studs make me unease. All the time I put WD40 down the studs. In the end, I usually go with home cut oak wedges to brake the seal.

 

[tdskip]

From another site - not my text;

"Since there has been a lot of discussion lately regarding removal of
recalcitrant cylinder heads, I thought I'd throw in my $0.02.

I recently yanked the engine from my parts car, and needed to remove
the head. After removing all of the stud nuts, the head was still
firmly attached to the block. The engine was frozen, so the much
touted rope trick was not an option.

What I ended up doing was tapping around the head with a rubber
mallet, and prying (gently) between the thermosat housing and the top
of the water pump to get the seam between the head and block to open a
bit. Once I got a foot-hold, I embarked on a 4 day-long process of
inserting (i.e., pounding) ever larger wooden wedges all around the
seam. The head was not really loose in any sense until I cleared the
last 1/2" at the top of the studs. Some things that I learned from
this that others might benefit from:

1) Use a tough, stringy wood for the wedges. Oak and ash worked
best. Maple was worthless.

B) A gentle smooth slope on the wedges is essential. Even so, the
wedges will break up as they are hammered in.

III) Initial progress is made in small increments. I got less than
1/2" of separation in the first three days.

d) The head gasket will get in the way.

By the time I was done, there was an impressive pile of wood chips on
the floor, but no metal was damaged."