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MG TD TF 1500 - Replacing Head Gasket

Hi all,

Pretty sure I have a leak in my head gasket, oil is getting into coolant, removing cap while running I see the telltale bubbles. For anyone that has read any of my prior posts you know I'm a beginner at this stuff, everything I've learned about cars I learned through this forum and YouTube, but was wondering if this is something that a guy with half a brain could do or is this something for an expert at the shop.

Steve
SD Denham

It’s something you could do as far as the removal and installation. Everything is reasonably easy to get at. You ll need a few Whitworth sockets, a torque wrench, a 1-1/8” socket for the crankshaft or your starter handle and a Work Shop Manual is helpful for the first timer.

To clarify oil is in the coolant? Or coolant is in the oilpan? Bubbles in the radiator is generally a head gasket issue. But could also be from a cracked head in rare instances. To confirm where the head gasket failure is, pull all of the spark plugs and do a compression test. You will likely see lower readings in adjacent holes. Like cylinders 1-2 or 3-4. The important thing to consider is why did it fail? Did some head stud nuts loose their torque setting, did a stud stretch or loosen in the block? Is the head and/or block deck surface(s) warped?

IN GENERAL TERMs for a LHD
To remove the head:
Disconnect your battery
Disconnect the fuel supply line at the carb
Disconnect the throttle linkage and control cables
Disconnect the carb vent tubes
Remove the 4 intake/exhaust manifold stud nuts
Remove the valve cover vent hose
Remove the intake setup as an assembly.
(You may need to drop the radiator brace to do this)
You should be able to slide the exhaust manifold off of the studs unless the headpipe still has a hanger at the transmission preventing movement. Remove the hanger and let the manifold fall out of the way.
Remove the valve cover and loosen the tappet cover.
Remove the four bolts at the front of the head retaining the water elbow
Unlock and back off all the rocker adjustments
Back off the rocker pedestal bolts at an even rate so as not to bend the shaft and remove as an assembly
Remove the pushrods.
Remove the head stud nuts
At this point the head should lift off. A small lever may be needed to pry it loose

Once the head is removed it is a good opportunity to have it refreshed by a competent machinist. If the head surface isn’t true a very light skimming is in order. Take off only what is needed to true it up taking fine cuts. While at the shop have the guides, seals, seats and valves inspected for wear and replace as needed. If the car is a high miler then consider replacing the valve springs if any don’t check out to specification.

You will require a cylinder head overhaul gasket set. In addition I highly recommend Tom Lange’s silicone roadster gaskets for the rocker and tappet covers. You ll never have oil leaks from those locations ever again and they are infinitely reusable. You’ll never use cork gaskets again. You’ll also need a spray can of CopperCoat to use on both sides of the new head gasket to help it seal. If the rear head plate is heavily pitted internally I also recommend Toms stainless steel end plate and his stainless steel thermostat housing that accepts a modern thermostat. The additional advantage to his housing is that the thermostat can be replaced easily through the top of the housing without having to pull it off the engine to replace it from the bottom as others on the market are so designed.

Once you get the head back on and torqued in sequence and to spec
per the WSM and all is back together you can warm the engine up to operating temps. Shut it off, pull the valve cover and retorque the head again. Double check all your rocker arm clearances and reset as needed and button the valve cover back up.

I will then retorque the head one more time at around 200 miles.

Hope this helps

Bill Chasser
TD-4834
W A Chasser

I will add one thing to Bills list. Drain the radiator. This will also give you a good picture if a radiator flush is indicated. If the fluid is green or green brown. That is normal. If it is dark rusty color, a flush is probably in order. You can flush the radiator by just opening the petcock and putting a hose in the top.

Flushing the block is probably needed also, but it is better to be done with an intact head gasket, so it may need to wait until you get the head back on.

Also, I recommend putting a piece of tape on each of the push rods and numbering them from where they came out.

When you take the rocker assembly off. Take care to note any spacers under the rocker towers. There may not be any, but if there are spacers, you want to make sure they are returned to the correct tower.

Find a good machine shop in your area to check the head for cracks and to check how flat it is. A good shop will tell you how it is and if it needs anything done to it.

Get a good head gasket. Payen have worked very well for me.


This is a good project to learn more about your car. Removing the head is not difficult.


Get a good gasket.
Bruce Cunha

Before removing the head.
Take off the cover plate at the rear of the head, awkward but do able. There is a small plug screwed into the rocker oil gallery, check this is tight ( you may need to make up a right angled screwdriver).
If has any looseness, tighten it up, flush out the coolant system and try the motor again.

Ray TF 2884

Ray Lee

This is a perfect example of the hip-bone being connected to the thigh-bone, the thigh-bone being connected to the knee-bone, and so on - so many engine parts around the head are interconnected, that you now have a chance to check on and make right. Some would call it a can of worms...

I will add that you will remove the oil line bolt from the head (save the copper washers).

Also, the head studs are a common problem with a blown head gasket, since they are usually the originals, and have been tightened and loosened many times before, and often abused. The slightest stretch in the stud threads will negate any attempt to provide accurate torque, as the stud will stretch rather than clamp. My head studs (mgtrepair.net) are the best available.

As a matter of course, I would replace the valve seal o-rings, whether you need valve work or not.

Finally, look carefully at the tips of the rockers, which should be smooth and nicely rounded. If there are depressions and unevenly worn places, the rocker gear should be rebuilt (which will also improve your oil pressure). Rocker Arms Unlimited are my choice.

If you are feeling daring or committed, remove the side cover and look at the tappets - they should be flat and smooth. If there are concave surfaces or pitting, your cam and lifters are not long for this world. Sorry.

Tom Lange
MGT Repair
t lange

Thanks Bruce, Tom and Ray for your comments. I knew I would surely miss a few details. As Tom said, you could be opening a can of worms of unforeseen problems developing and that now would be the time to correct them or at least be prepared to deal with them soon. While components are apart it is advantageous to observe, repair or replace any item that is worn. This saves you both time and money in the long run. You’ll have more happy motoring miles without the need to go back into that particular part the engine to do further repairs of something you missed.

If you do inspect the lifters/tappets, insure they are returned to their respective cam lobe. There is no need to pull them all out at once.

What you decide to do will be your own judgement call to make. We are collectively trying to give you much of what to look for and options for you to consider.

Bill Chasser.
TD-4834

W A Chasser

I know it must seem as though we are piling on, but we are really trying to help you deal with the short-term/long-term needs of your car.

Bill is right on when he points out that each lifter needs to be kept in its original position; I take them out one at a time. If one is bad, they all will need re-surfacing, and your cam will also need at least a re-grind. I use Delta Cam for both, their RV grind is a good one.

This is also a perfect time to check your water pump (if there is ANY wiggle in the fan blades, have it rebuilt), thermostat for proper operation (suspend it in an old pan, heat the water to boiling, and watch when the thermostat opens), and have your distributor rebuilt. Having the distributor gone through by Jeff Schlemmer at Advanced Distributor is the very BEST bang for your buck in terms of smooth running and good power.

Tom Lange
MGT Repair
t lange

2 tricks about tightening the studs with the specified torque.
They must be oiled, on the threads and under the head and washer.

When retorque, unscrew 1/8 turn and then tightened to the specified torque.

Laurent.
LC Laurent31

You have opened a can of worms there! See the archives. Washers?
Dave H
Dave Hill

Awesome guidance, info and comments all, I really appreciate it. I don't know if I want to start this project now as we're just getting into nice weather and I foresee with my schedule proceeding with this project could be a few months at least, maybe start in the Fall. Lots to digest and learn! Love my Dad's MG, whenever I'm driving it I know he's in the passenger seat having a grand old time :-)
SD Denham

Where in CA are you? Surely there is someone nearby who can help out.
Steve Simmons

Yes if your near me I’d be willing to lend a hand.

Tom and Laurent also added valid points.

I use hardened washers on all my head studs though originally they weren’t provided. Tom Lange’s ARP studs are offered with washers and 12 point nuts. Though they are a bit pricey (due to their engineering and special production runs) they are worth every dollar spent. In fact every item Tom sells is of the highest quality and detail. I have no financial interest in my endorsement. Just a very satisfied and repeat customer. Of course if Tom were to give me an additional discount on my next project I wouldn’t turn it down. LOL. Just kidding Tom

Bill Chasser
TD-4834
W A Chasser

Bill - I'll look into it...

To make one small correction to Bill's post above, with my head studs one does NOT need washers, and I do not normally supply them. Washers were recommended by the factory for use when the head was planed to raise compression - the factory was concerned that because of inevitable variations in casting, one might run out of stud thread on a high-compression engine.

Among other improvements, my stud adds 1/4" of thread to the stud, to accommodate thinner heads. A head would be un-usably thin before one ran out of threads when using my head studs, which is why racers use them with total confidence on high-compression engines.

The only time when washers are recommended is when using an aluminum Laystall Lucas head; I supply special ARP hardened, parallel-ground washers for that application.

I appreciate the kind words, Bill.

Tom Lange
MGT Repair
t lange

Thank you Tom I stand corrected, well sorta. I was installing a Laystall when I got them from you. Lol

Cheers

Bill Chasser
TD-4834
W A Chasser

If not mentioned above, it might also be worth undoing some of the head bolts and check if the area near the bolts have raised and formed a low volcano around the bolt hole - may be of earlier over tightening of the bolts. I faced that problem and after grinding them down carefully, I have not had any problem with leaking head gaskets.
YS Strom

YS - do you mean head studs?

Conventional wisdom is to professionally re-surface the block to guarantee it is absolutely flat. I seldom recommend this (it rarely needs it), but I DO recommend running a small oiled whetstone over the entire block surface, to remove the small ridges that tightening the studs can produce. I assume these are what YS is referring to. With a whetstone it is easy to see where a high spot is being knocked down, and when the area has been fully flattened.

Tom Lange
MGT Repair
t lange

t lange

Yes, I ment head studs.

Got a leak after 60 km, between cyl 2 and 3, after having installed a resurfaced top. Tried a glass plate and sand paper to level the block, but this was not enough, so used a small grinding machine to get rid of the volcanoes. Fortunately it happened near a friends workshop, so I could borrow a grinder, but 70 km from home at 5 pm. it was not the right place to take out and resurface the engine. After grinding the block and installing the old gasket - need no comments on that - it has now worked well for a year.
YS Strom

To clarify it, I meant I need no comments on re using a gasket, but it is interesting to note that it is possible.
YS Strom

May I add: Step one - Completely remove the bonnet.

Step two - Create a rack to hold the push rods in proper order (holes partieally through a 2x4 will work) and a rack to hold the rocker assembly and related parts in proper order.

Step three - make sure your digital camera has room for lots of pictures and photograph every step from several angles to help your reassembly. This step is also useful when you inevitably have a question for the BBS.


Jud
J. K. Chapin

Also, there is a long thread started by me a couple of years ago chronicling my adventures of head removal and re-installation after I sucked a bolt into the #3 cylinder. I've tried to search for it but am woefully inadequate in running the BBS search engine. Maybe someone else can find it and, I also think one or two members offered to host a summary of the thread on their site so maybe they remember it. Anyway, there may be a few real goofs by me that you can avoid by reading the thread. I know a lot of theory about internal combustion motors but have (had?) little in the way of practical hands-on experience. If I could do it, you surely can.

Lastly, I second that Tom's stuff is great. Go with his stuff.

Jud
J. K. Chapin

Jud -

That was a great thread. I saved it as a PDF so that I can refer to it.

The thread title is "Ominous Engine Rattle"

The link is
http://www2.mg-cars.org.uk/cgi-bin/or17?runprog=mgbbs&access=&mode=archiveth&subject=8&subjectar=8&thread=2014091615331219727

Note: The link will change if someone reactivates the thread.

Lonnie
TF7211
LM Cook

Thanks Lonnie. I couldn't remember the clever title I used but I new it was eerie.

Jud
J. K. Chapin

Using something that does not scratch the aluminum, scrape/clean all of the carbon off of the piston tops. Check the bores for major scoring or problem. As mentioned above, I would change radiator hoses, replace thermostat, etc. and anything else you have removed. I would remove the carbs from the intake, temporarily assemble the new manifold gasket and intake manifold, and check for steps or gasket overhang. It should be smooth and flush. Service the carbs while they are off. A cardboard box works well for keeping pushrods in order- just punch holes with a large Phillips screwdriver in the box and number 1-8. A Styrofoam egg crate works for tappets. It is imperative you keep them in order! I second Tom's head studs and thermostat. George
George Butz III

This thread was discussed between 29/04/2018 and 01/05/2018

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