My 76 continued

[spitfire]

Well I finally got the head off. Wasn't as difficult as I was making it out to be, I just missed the 4 nuts on the rocker assembly.
Anyway with that all off, there are no cracks in the head, the head gasket appears to be in good shape and I don't see any cracks in the cylinder walls, well the two that I can see anyway, I need to move the other two to tell for sure. but the bores seem to be fairly clean.
I took some pictures with my phone but will need to wait until i am home with a better PC before I post them.
Push rods were covered in white sludge, or the broken down oil. The various holes have corrosion in them and need to be cleaned. There appear to be mineral deposits on the inside of the head. But overall there isn't anything that looks to be causing 0 compression. So I am at a loss there.
However now I don't know if I should pull the block and send it somewhere for professional cleaning and then get a new set of gaskets and bolt it back on. Or make the attempt at just cleaning it all up myself and put it all together with a new set of gaskets.

[Jimmy]

You'd be surprised what you could clean out with a quart or two of ATF in the oil...but that pretty much requires a running engine.

[Steve Simmons]

Did you perform a compression test before pulling the head off? If so, what were the numbers. Sometimes cracks can be hard to spot visually. A head job will run around $200 and you can have the head magnafluxed at the same time, which will tell if there are any cracks. If there really are no cracks in the block or head then it probably just blew a head gasket. That's an easy fix by itself. The rocker assembly should be cleaned and inspected I suppose, but so long as it all moves then you could at least try running the engine as-is.

[spitfire]

I did run the test and I got 0 in all 4. I will post pics of the head and block tonight after dinner when I get back to LA.

It's so fun driving an hour just to work on an engine.

[Steve Simmons]

Maybe you should take the engine home with you!

[spitfire]

So here are the pics I promised, taken from my iphone.
The block

The head

[Steve Simmons]

Doesn't look so bad to me, really. I don't see anything that screams "no compression on all four".

[spitfire]

I know thats my problem with it. I just don't understand why i was getting 0 in all four. So a new gasket set and have the head machined and fluxed I guess. but that will have to wait until after the honeymoon.

[HealeyBN7]

I am no expert in MG engines, but it does look like the top ring stops pretty far short of the top of the block.
And I guess it is the lighting, but what is that "dent" in the back of cylinder number 4? Even with sketchy rings, zero compression across all four is a brain teaser. Broken compression gauge?

[spitfire]

What you see on number 4 is present on all of them, and they are all smooth and the gasket has cleareance for it. So I saw it too then noticed it on all 4 so I didn't think much of it afterwards.

Hmm, the possibility of a broken gauge is there, I rented it from the local kragen near where the car is parked.

However when I got the car it wasn't running and the previous owner was told by a mechanic that there was a crack. So that is what I have been going with for the last year.

But like I said further investigation will have to wait until after I return from my honeymoon in May.

[Steve Simmons]

The "dent" could be a relief for a valve, but it's pretty deep and I don't see it on any other cylinder. See attachment...

EDIT: Just saw Spit's reply that it's there on all four. Must be for valves then.

[Jimmy]

Yep, they're for valve clearance.
Seems that motor's been rebuilt at least once.
But don't ever assume that something's cracked just because the seller said so.

[HealeyBN7]

Hard to believe they couldn't get the valves to fit. Interesting design. I guess I don't get around a lot.

Do those pistons really stop that far below the deck? I am looking at a picture of a MGB piston on ebay. I am guessing the top ring is only 3/16" from the crown. Based on the markings in the cylinder walls, either the other rings are broken, or the piston stops 3/8" from the deck...

Dean

[spitfire]

Yes, there was at least one rebuild on it that I am aware of some time in the late 90s. It became a non-runner on 01.

[Jimmy]

Based on the markings in the cylinder walls, either the other rings are broken, or the piston stops 3/8" from the deck... Dean

Which could explain the low compression.
On the other hand, the motor would likely run quite comfortably on kerosene now.

[spitfire]

I see what you are saying about that cylinder wall. I guess the next step is taking out the cylinders and see what I can see.

[Steve Simmons]

If you can feel a "step" where the silver meets the stained area, then I'd guess a rebuild is in order. I can't imagine that not a single ring is left intact. If all cylinders have zero compression then I'd guess the head was loose and the gasket was completely trashed. I just can't imagine it being anything else, unless the goo on the valves is preventing them from closing fully yet allowing air to escape. If it were my engine, I would be tempted to do a head job, pull the pan off to inspect the bearings, and if all looks good down there then put it together and see what happens. That's maybe $300 worth of parts and labor. Then again, you could probably find a running engine for that much.

[HealeyBN7]

If all cylinders have zero compression then I'd guess the head was loose and the gasket was completely trashed. I just can't imagine it being anything else, unless the goo on the valves is preventing them from closing fully yet allowing air to escape.

I agree, the "zero" compression is real hard to understand. I don't see how you couldn't get 40-60 even with many many bad rings. My Hudson sprayer gets an easy 25 psi with just a couple pumps... That's why I thought the gauge might be suspect or perhaps the starter was spinning very s l o w...

Dean

[VWNate1]

I see what you are saying about that cylinder wall. I guess the next step is taking out the cylinders and see what I can see.

I'm pretty sure you mean taking out the pistons but DON'T ! you want to drive and enjoy this car , right ? . the cylinder bores *look* fine (yes , I know computer pictures hide a lot) so be smart and drop $250.00 ~ $500.00 into having the cylinder head magnafluxed then rebuilt . if the guides are still cast iron , have them ALL replaced .

I'm sure the guys here know a competent & honest Machine Shop (my guy retired dammit) , once you have the head ready to go , invest the $ in a good quality copper head gasket (those silver coloured tin ones SUCK) and use some Permatex Copper Kote spray on both sides of it before buttoning it up .

These engines are *very* low compression and so will run quite well even with Uber high miles .

When you torque up the cylinder head , have the shop manual open to the diagram and follow it exactly , the idea is to apply the clamping pressure from the center outwards equally . this overcomes the mediocre design and old age issues that cause so many of these sturdy engines to weep , leak or blow head gaskets .

I personally torque them in multiple stages beginning @ 5# and repeating going up in 5 # increments , I've never blown a head gasket after doing this .

I assume you know this engine has been cobbled up out of spare parts (the dizzy is a pre 1968 one) - the engine serial number prefix will tell if it's a '76 engine or what .

If it is a 1976 engine , there's a simple repair to increase power greatly once you have it running again . no rush , one step at a time until you have a nice car that runs well .

You're at the one day's work point now , send the head out for rectification and then proceed , the guys here will walk you through this simple repair and soon you'll be zooming down PCH with the top down , watching the sun set

Don't worry about the zero compression test , it's not possible , the gauge was bad ~ a typical loaner tool .

[spitfire]

Yeah, so I guess I should update with some, um, updates?

Took the head over to Malcolm, his guy did a great job, new seats, machined and a valve job. The block is next and then I get to buy all new seals.

Also I am looking for an apartment in El Segundo with a garage for a reasonable price so that I can move the car closer to me and actually get to work on it regularly.

[Steve Simmons]

Did you magnaflux the head? If it wasn't cracked then what was the previous owner talking about? I hope the block isn't cracked!

[spitfire]

It was magnafluxed, and there was a crack, but it was repairable.

[Steve Simmons]

The kind of crack that would spill coolant into the oil? If not, then you'll have to find the cause before you put it back together!