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MG TD TF 1500 - Head Gasket

Möbius just blew its head gasket. It either doesn't like the name or is trying to live up to it. I wont know all the details till I take it apart.

Yes, lots of very white smoke, no power, running ragged. When I pull plug wires 3 & 4 no change in the engine idle. When I pulled the plugs 3 & 4 steam from both cyclinders. Hope it is just the gasket.

I need some advice from those of you that have done this before.
Do I need to take the engine out?
Can I just pull the head?

Any sage advice for the project would be appreciated.

What are the chances of completing the job by Friday so I can go to the Bits on the Beach show(Ocean Grove, NJ)on Saturday?

Mort TD 1851

Sorry to hear this Mort,,,
You do not have to pull the engine if it is only the gasket,, We did it on the side of the road on the skyline drive trip,,, have the head checked for straigntness,,

SPW
STEVE WINCZE

More,,,
Bonnet must come off,, drain coolant,, Either a round hole or a banana hole gasket will work,,
keep all push rods in order and put them back in the same holes,,,

SPW
STEVE WINCZE

Steve is perfectly correct; pull the bonnet and then have at it. Everything comes right off. Replace the valve seal o-rings and do have the head checked and possibly re-surfaced (have them take as little off as possible). I also pull the head studs and run an oiled whetstone over the block surface to look for any warpage there (you can see the polish marks for high and low spots). And check the head studs for any stretching - it looks like the threads are thinner or hourglass shaped (I sell wonderful racing-quality ARP head studs).

While it's apart... Have the valves hand-lapped if no valve job is needed, check the rockers and shaft for wear (Rocker Arm Specialists do a great job of rebuilding if needed), and check to see if there is a big ridge at the top of the bores. It's also a good time to check the distributor shaft for any wear (Jeff Schlemmer, Advanced Distributor is the man).

And let us know how it goes!

Tom

t lange

A little more,,,
Even though you have just built the engine and there are not many miles on it,, to be on the safe side, I would replace all of the manifold gaskets with new ones,,

SPW
STEVE WINCZE

Sorry, I didn't know it was a fresh engine. be sure you torque it down well, run it for a bit, then torque again. You'll be amazed at how much re-torque is needed the second time to get it back up to spec.

Tom
t lange

I am not sure but I think it is not advisable to use a round hole head gasket with either a banana hole head or block or both. As I remember it, a round hole gasket leaves a potential for another coolant leak. Other BBSers, please check me out on this. Could save Mort from a chance to a repeat performance.
Jim Merz

Thanks for the comments. Please keep them coming. I am disassembling components now and want to place an order for gaskets.

Steve,
This is not a fresh rebuild. It is just the way it was when I bought it a year ago. It is one of the few things I have not taken apart yet.

Please alter comments as appropriate.

TIA,
Mort
Mort TD 1851

The rule of thumb on gaskets is that you can use a round hole gasket when you have a round hole block and a round hole head. With very sincere respect to Steve, in every other case, banana hole block and banana head, banana hole block and round hole head, round hole block and banana hole head, you need to use a banana hole gasket. Seriously. Some of the leaks I've seen when using the wrong gasket have been very impressive. Yes, once in a while it seems to work, but why do it twice?

Attached is a picture of a round hole gasket that was used with a .100 over bored out banana hole block and banana hole head (in the mistaken advice from Moss that the regular head gasket might overlap into the bores). Notice the impressions of the banana holes, and how they will interface with round holes in a gasket, but round holes won't seal bonana holes because of the round ridge meant for the round holes.

I hope this makes sense.

warmly,
dave

Dave Braun

Have the machine shop check the head for cracks also. I have seen a lot of bent pushrods and loose rod ends, so pull them out (keep in correct order- punch holes in an upside-down cardboard box and label 1-8, etc.). Roll each pushrod over a flat surface and make sure it doesn't wobble. Also check VC and manifold studs for stretching- besides "hourglass" shape as Tom mentioned, you can feel the thinning/stretched areas by lighty running your thumb/forefinger lenghtwise over the threads. Might as well go through the carbs while they are off if not already done. Get the exhaust manifold coated too. Realize this could result in total restoration of the car if carried to extreme! I would put Tom's new studs in anyway if my engine was apart. George
George Butz

IS the car Supercharged?
Tom Maine (TD8105)

Thank you all again. I have ordered the banana hole gasket on the assumption that it is proper for my engine. TD 1851 Engine 1606.
Whitworth socket set should be here tomorrow and I will complete the disassembly.
Mort TD 1851

About the only car engine easier to replace a head gasket on that I can think of... an old flathead.

Pretty straightforward.

But, it reminds me of a few years ago when I received a head gasket from one of our reputable suppliers.... it was in a box, folded in half!

Yesterday, I received a couple of Honda head gaskets sandwiched between 2 pieces of cardboard, bent in the middle about 30 degrees. Not good! Got 2 replacements on the way.
Jim Northrup

i don't know anyone hand lapping valves any more. as has been explained to me by two machine shops, the angles ground on seats and valves are complex and hand lapping is no longer done. regards, tom
tom peterson

It's all a matter of opinion. I hand-lap valves because when I put gas in the complete combustion chambers of heads done by 3 different shops, all leaked a little drip of gasoline down the valve stem. After I lapped them with the finest valve grinding paste I could find, they didn't drip. QED. Maybe it only makes 1% difference, but that's worth it to me. I even do it again after a thousand miles or so, but again, that's me.

I have never had a come-back, and have never had a valve job last less than 52,000 miles. I'm OK with that, but it's all a matter of opinion. When I do an engine I charge $25 to lap in all 8 valves the first time, and $100 to re-pull the head, re-lap and re-install everything after a thousand miles.

Maybe I just enjoy doing it, and it gives me a chance to check up on everything.

Tom Lange
Bar Harbor, Maine

t lange

Dave B.,
Thanks for the clarification on the holes!,,,
.
FYI,, One thing that I also do when taking something apart something like a cylinder head that has a tourquing sequence for assembly, is to relieve the tourque on each the nuts in that sequence a little at a time when taking it apart,,, Might be over kill, but I think it is worth the effort rather than undoing each nut completely, then moving on the the next one,,,

SPW
STEVE WINCZE

Update.

Sockets arrived and the good news is that it appears that it is only a blown gasket. Gaskets are on their way.

Although I have no history at all this engine must have had work done recently(by milage). The rockers are fine. Nice and convex without even flats on them.

The number three rod is definitely bent. Two others have a slight distortion and the rest are ok. Is it advisable to replace just the bad ones or should I replace them all?

I had a lot of difficulty removing the head. I could not pull up. I did tap with a block of wood and a hammer. I could rock it a bit and get maybe 1/16" clearance. I have a lot of composite shims and worked them around until I got the head to just past the end of the studs. Then I could lift it off. I also had difficulty removing the gasket and had to work it up a little at a time until I got it off. I am assuming the studs are not true and are applying lateral pressure on the head and thus resisting my puling it off. I plan on replacing the studs.

Whats the best way to remove the old studs?

Looking inside the head I see very little rust.
The cylinder walls are all clean with no scratches.
The top of three pistons have a bit of carbon deposit and number 4 is nice and clean.

I tried scraping the carbon off the pistons but saw the carbon going between the piston and the wall so I stopped. What is the proper procedure for cleaning the pistons without further breaking down the engine?

Thanks again.
Mort


Mort 1950 TD Möbius

Tom Lange,
When you re-lap at 1000 miles, do you replace the head gasket? I would like to re-lap the valves we installed a few months ago, but was reluctant to do so since we are currently using two head gaskets. (By the way, you must have been an awfully good person in some previous life, to be able to come back and work on MG's in Bar Harbor, Maine.)

Sorry to hijack your thread, Mort. Best of luck with Mobius.

Safety? Fast?
Scott Ashworth - '54 TF
S. R. Ashworth

SR - I have not needed to replace head gaskets then, unless I have damaged or disturbed them in removing the head. I do re-torque multiple times, as I wrote earlier, using a short socket to fit under the rocker gear. Re-torqueing takes minutes, since I have nothing to remove, but I do then re-adjust the valves.

And yes, Bar Harbor is pretty amazing, even though getting cars transported here always costs the earth because we are not on the way anywhere except Canada. The ocean is just a few miles away, I have raspberries, apples, pears, blackberries and blueberries, and two kids, 9 and 11 to keep me young.

Hope this helps.

Tom Lange
Bar Harbor, Maine

t lange

You can either use two nuts on the stud, tightening one agains the other and then screw out the stud or get a stud remover. About 10 bucks and just screw the studs out. Not a real problem. I bought my stud remover at Harbor Freight and used it to pull my studs during my rebuild. It is a tool that has a gripper on it and you use a socket drive to turn the stud out. I would go with new studs if I were you, you dont know how many times that that have been torqued on over the years. not cheap but worth it.
Tom Maine (TD8105)

Mort,

My website shows me removing studs. http://www.dbraun99.com go to the mg td15470 section and look up the engine work. I used the double nut method. It is corrosion between the studs and the head that most often causes difficulty in removing the head. The fact that you got it off this quickly says the corrosion was not too bad. But I'm in the replace the studs camp if they show corrosion or permanent deformation due to torquing. If they look 'normal' they aren't over stressed. Steel has an ultimate yield point where it doesn't spring back.

I take it you have a bent push rod. I would replace the single push rod. Measure first, as there are two different rod lengths.
Dave Braun

An easy trick to free up a stuck head is to feed a length of rope trough the spark plug hole and turn the engine with the crank. The piston will push the rope up and lift the head.
-David
D. Sander

If I may. The double bolt works, but if you are purchasing a remover, do not buy the cam stile. These put marks in the studs and may not remove the stud.

I recommend having a set of these in your toolbox

http://www.jagorequipmenttoolandsupply.com/Products/template.asp?Item=1663
Bruce Cunha

Bruce, you are right about the cam style, I replaced all my head bolts when I did mine. Although they leave a mark it can be overcome with either a thread chaser or die. A lot of the head bolts have been torqued over time so that they are no longer viable.
Tom Maine (TD8105)

Thank you all for all the good pointers.

I am replacing the rods and studs and nuts. All from Tom Lange.

The head is now at the machine shop. More news tomorrow.

Mort
Mort 1950 TD Möbius

Bruce,
Thanks for that link. It's on my Xmas list.
Mort
Mort 1950 TD Möbius

When rolling pushrods for straightness on a flat surface, roll only the rod part, not the ends - they are often not round and will give a false indication.

And remember, I do sell highest-quality ARP head studs, 12-pt. nuts, and have a few sets of NOS ISKY pushrods left. The pushrods sold by the usual supplier cost more than mine, are indifferent quality and vary greatly in length.

Tom Lange
Bar Harbor, Maine
t lange

This thread was discussed between 14/09/2011 and 16/09/2011

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