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Cyl block damage repairable after blown head gasket ?

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3727839 by Rick Fawthrop The photos indicate the liners are cracked and the pistons are scuffed.
My opinion is that it is not cost effective to replace two liners, two pistons, a cast iron weld, and the machining of the deck surface and the top of the bore, and the repairs to the head.
If you can find a shop to do the work and find the parts.
But that’s just my opinion, actual results may vary.

I don't see any cracks or scuffed pistons... but I do agree with the rest of your post. If a quick attempt at brazing the gap with the engine in place didn't work I would pull the engine and see if a machine shop could replace the liners in a cost effective manner. If that wasn't possible I would start over with a new block.

Of course, I have welding equipment and I know how to use it. I have repaired cast iron items before with good old fashioned bronze and a gas welding torch. That looks like a 20 minute job to me... if it was in my garage... ymmv. I would either ruin it or fix it. cool smiley

Adrian



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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
That block is toast, that happen because the engine was driven too far after the head gasket failure. Sometimes a tow truck is a bargain.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 1 time(s). Last edit at 2018-05-01 01:24 PM by Speedracer.


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HiPowerShooter Avatar
HiPowerShooter Gold Member James Booker
Lake Winneconne, WI, USA   USA
1973 MG MGB
I told my kids when they were first learning to drive that if the car/truck started overheating enough for a light to go on that they were to pull over immediately and shut it down. Takes only a minute or two for heads(especially aluminum) to warp and blow the head gasket. MGB isn't a big deal. Two hour job once the head and gasket are ready...not so easy or cheap in a newer car.

In reply to # 3727969 by Speedracer That block is toast, that happen because the engine was driven too far after the head gasket failure. Sometimes a tow truck is a bargain.



"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

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73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...

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Rick Fawthrop Avatar
Rick Fawthrop Richard Fawthrop
Langley, WA, USA   USA
Adrian in the top photo there is a visible crack across the top and another crack 2 mm down into the bore running horizontally.
The second photo shows piston material deposited onto the liner from the top going down four mm. The discoloration and scuffing is from the rings bound up in the ring lands.
That liner is never going to seal water.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
I think we have pretty much figured out that we would both handle this differently Rick...

It will be interesting to see what Geoffrey actually ends up doing.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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sweep Avatar
sweep Gold Member Chris W
Gosford, NSW, Australia   AUS
1966 MG MGB "Basil"
2013 Volkswagen Tiguan
2015 Audi A3
Notwithstanding my earlier comments, I have difficulty visualising how this sort of damage can occur. Sorry, that's not correct. I mean, how the car could be driven to the point of that much damage without the driver getting an inkling that something bad was happening.

When my head gasket blew a few years ago it was BLATANTLY obvious that something bad had happened. The noise and loss of performance was instant and profound. I drove it about 200mtrs to get it somewhere I could leave it and when I examined the flame path in the block and head I could still see machining marks.

Was the gasket already breached before you bought it and therefore not get the opportunity to drive it before the failure?

BTW, I still think a bodge fix is worth a go but only if you're doing it yourself. If your paying someone....well, you know the answer to that.



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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
I've have seen one time before, new MGB racer at first race with new and very nicely done MGB race car. The car developed a horrid miss early on Friday, and he just kept driving it multiple sessions with this horrible miss, I get it, he just wanted track time. Once the problem was diagnosed , we offer to help pull the head and changed the gasket, but he was weary about doing this at the track. Once he got home and pulled the head, the damage was obvious, both block and head has burn grooved. This guy has did his engine right, I supplied him aftermarket rods and piston, cam and few other parts Dave has supplied with head and rockers arm and few other goodies. The reason for his failure was way too much advanced ignition timing for a high compression race motor, and continuing to drive the car on track after the gasket failed . This type of failure doesn't happen immediately, you have ignore it, and continue to drive the car for some time for it to get this bad.

I can tell you right now, there is not a quick fix for this, any type epoxy is not going to do it, heat in this area at time of ignition is well above what any epoxy type repair could stand up to. It might could be weld repaired, but that too would be risky and probably cost more than prepping a new block. The other question would be did the head suffer the same fate, if so that might be a more reasonable weld repair, it needs to be done by someone well versed in cast iron welding, assuming you have a cast iron head, someone really good at nickel, or spray cast iron welding.


Another thing to look at is what head gasket was used for this big bore build, what the CR was and what was status of the fuel mixture, and ignition timing?



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 1 time(s). Last edit at 2018-05-03 06:49 PM by Speedracer.


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Nickh6511 Avatar
Nickh6511 Geoffrey Huggonson
Orleans, France   FRA
Adrian, Rick, your opposing comments have helped me sort out what I want to do.
Hap, your last post is on the nail!
Thanks all

As I bought the car without trying it, I put the roughish idle down to the fast road cam, as it ran OK. When it went rough on the way home, I was on the Paris périphérique in rush hour at night. (At least it wasn't raining) So tried to get off the 6 lane gridlocked mayhem to have a look, until it overheated then I stopped. Distributor loose, so turned it back until it started and ran as before. Filled up with water and no further overheating

Set timing by advancing until difficult to start then turning back- no pinking.

Ran fine for 500 miles over 4 months up to morning of first ever slalom, filled up with petrol 98 but then went rough 10 miles short of destination. Got there by running gently but pinking badly, but not overheating. Thought the petrol might be bad (dirty, wrong grade, water in it, dunno but coincidence after filling up).

Decided to do one run of slalom (1200 metres/yards). Brilliant fun, but overheating at end. Bubbles in radiator then did compression test. Got towed home by kind Lotus Elise driver.

So after your comments and the end result, I'm obviously not as mechanically sensitive as I thought! But I really wanted to have 1 go at the slalom...

Taking the head off showed that head nuts were easily movable with a short wrench, not tight at all, and the gasket was drowned in oil and water.
Gasket is black with no identification. The head looks OK - only the valves won't hold petrol so will lap them in.

My plan is:
1. Look for someone who can grind back the iron between the liners, and tack on some weld onto the liner tops, clean up and flat.
2. If nobody is willing, take bottom end apart and check pistons & rings, crank & bearings. If OK try to get another block with liners machined for 2000cc for current pistons.
3. If not, buy a block & pistons at 1950cc.
4. IF not any block and piston set. or complete headless engine

Last question - Could I skim the block down to get a flat surface (around 1,5mm) Engine builder Ivor Searle says CR is around 9.5:1. Would skimming increase the CR too much ?


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Rick Fawthrop Avatar
Rick Fawthrop Richard Fawthrop
Langley, WA, USA   USA
Geoffrey, let’s start with your head first.
Get a straight edge and some feeler gauges and check the head for straightness as per the factory service manual.
Then send out the head for machining. At least surfacing and magnafluxing.
When the work is done get a burrete and check the combustion chamber volume.

Now getting to the short block.
Check the block for straightness. Check with a depth micrometer how far down the pistons are at TDC.
Tear the motor down. Clean it. Check for cracks. I expect the top rings to seized in the ring lands.
If that block is good, go buy a lottery ticket because you are on a winning streak.

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Speedracer Avatar
Speedracer Platinum AdvertiserAdvertiser Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3729345 by Nickh6511 Adrian, Rick, your opposing comments have helped me sort out what I want to do.
Hap, your last post is on the nail!
Thanks all

As I bought the car without trying it, I put the roughish idle down to the fast road cam, as it ran OK. When it went rough on the way home, I was on the Paris périphérique in rush hour at night. (At least it wasn't raining) So tried to get off the 6 lane gridlocked mayhem to have a look, until it overheated then I stopped. Distributor loose, so turned it back until it started and ran as before. Filled up with water and no further overheating

Set timing by advancing until difficult to start then turning back- no pinking.

Ran fine for 500 miles over 4 months up to morning of first ever slalom, filled up with petrol 98 but then went rough 10 miles short of destination. Got there by running gently but pinking badly, but not overheating. Thought the petrol might be bad (dirty, wrong grade, water in it, dunno but coincidence after filling up).

Decided to do one run of slalom (1200 metres/yards). Brilliant fun, but overheating at end. Bubbles in radiator then did compression test. Got towed home by kind Lotus Elise driver.

So after your comments and the end result, I'm obviously not as mechanically sensitive as I thought! But I really wanted to have 1 go at the slalom...

Taking the head off showed that head nuts were easily movable with a short wrench, not tight at all, and the gasket was drowned in oil and water.

M
Gasket is black with no identification. The head looks OK - only the valves won't hold petrol so will lap them in.

My plan is:
1. Look for someone who can grind back the iron between the liners, and tack on some weld onto the liner tops, clean up and flat.
2. If nobody is willing, take bottom end apart and check pistons & rings, crank & bearings. If OK try to get another block with liners machined for 2000cc for current pistons.
3. If not, buy a block & pistons at 1950cc.
4. IF not any block and piston set. or complete headless engine

Last question - Could I skim the block down to get a flat surface (around 1,5mm) Engine builder Ivor Searle says CR is around 9.5:1. Would skimming increase the CR too much ?

No, unfortunately you can't skim the block to fix this. THat is Cometic MLS gasket, made here in the US, they make them several ways as for thickness and bore size, lay the gasket back over the block, you have room for the the endge f the fire ring on the gasket , it not then they ordered the wrong size gasket. A normal Payen gasket is aprox .090" over stock, but 1950cc is like .130" over, so it requires a special big bore gasket, you have tow choice of big bore head gasket, the Payen copper, and the Cometic MLS, what you have, which was the better choice. Here's what I think form what you told us, the head was never retorqued, so that is probably wah caused this failure. Note there is some extremely bogus info out there, including from manufactuer tech, which says you have to have retorqued, this or that head gasket, this is 1000% fubar info, every head gasket ever used on a MGB need to retorque after about 3 heat cycles, regardless of what anyone tells you.

Ok your internals should be fine meaning piston rods, crank, all of that stuff could be transferred to new machined block, you'll want new rings, might as well do new bearing, and you need new gasket and seals. You could fix the block, but it is futile effort, it will cost more than getting and boring a new block, any attempt to fix it the block would questionable long term. Did the head have grooving in it you can feel, if not, you still need to resurface the head.

I know not what you want to hear, but I build these engines for a living, and this is what I would do if faced with the same delima.

Maybe since you are in France going to a MG professional in the UK would not be a bad idea, first person I would recommend to talk to over there would be Peter Burgess, a prince of a guy, great reputation, and very good at what he does.
http://www.peterburgessshop.co.uk/CylinderHeads.html



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 1 time(s). Last edit at 2018-05-04 08:07 AM by Speedracer.


Member Services:
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Nickh6511 Avatar
Nickh6511 Geoffrey Huggonson
Orleans, France   FRA
Well,
After 10 months of dallying with another classic (Ford Capri V6 2.8i) I found the motivation to strip down the MGB with damaged block (pics of gasket and block damage). The Stg2 head is skimmed and valves lapped, the springs look good so all put back together with new stem seals.
The engine parts are mainly looking good, its got a newish duplex vernier timing chain, the piston rings are complete and free. The dished pistons are 83,35mm diameter and marked STD and an arrow on the top (see pics). The crank and bearings are hardly worn in. Only the cam lobes and followers are showing any wear, and need replacing. Looks like they are older than the rest of the engine...

My objective is to get it back running reliably with a minimum spend.
An engine builder acquaintance has had a look and says welding will not work, but reckons that 0,6mm can be skimmed off the block to clean it up, and a similar amount off the pistons outer crowns, then clean up the bores. Around 300€/USD. Then buy cam and followers and gaskets, and put it back together.
The other alternatives I see are:
a. buy a block and bore and sleeve out to 84mm (with risk of boring through the wall thickness, and more expense)
b. buy a new short engine - need to go to UK to pay around 2800€/USD & transport

My questions are, to all I thank in advance for spending the time to reply:
1. Will this increase the compression ratio or keep it the same? Should I really measure the volume in the piston dish and cyl head to try and properly calculate the effects of the rectification?
2. Which cam would you advise to give good torque (to go with 2000 ish cc, Stg2 ported head, tubular stainless manifold, Weber 45DCOE)
3. What are the chances of this working out? :-)
4. If all goes well, I'm more of a SU fan than Weber, would it be more effective to find a pair of 1 1/2 SU and sell the Weber?

Over to you guys
Nick


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chris Avatar
chris Platinum Member Chris Roop
Pendleton, OR, USA   USA
He really thinks that .006" will clean that up? A short block is probably your fastest, cheapest, and most reliable option. I'd still buy a block to fit your parts.



Edited 1 time(s). Last edit at 2019-03-14 05:21 PM by chris.


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rdgreen Avatar
rdgreen Gold Member Robert Green
Adelaide, South Australia, Australia   AUS
.6mm Chris....023" imperial. Don't you love two measuring systems?

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cschaefer Silver Member Chuck Schaefer
West Chicago, IL, USA   USA
Years ago, I bought a boat with a Merc I/O engine that was frozen. As a neophyte shade tree mechanic, I pulled the engine, then the head and the oil pan. I broke out the 2x4 and tried to drive the pistons out to free it up. I found out too late that the pistons weren't supposed to come out the top of the engine. I broke 2 pieces off the skirt of the wet sleeve. I looked around an no parts were to be found in north America (It was a Renault block used in boats and forklifts here in the USA). I had a local welding shop loosely place the parts in reasonable location and brazed them together. I then took a Dremel sanding drum to clean up anything internal that looked like it would interfere. Since the damage was below the ring travel I figured what Have I got to loose? That engine ran a couple of years with no issues before I sold the boat. I'm not suggesting that this is what should be done. Especially when replacement blocks are easily found. But it did work. And if I were in the same situation, I might try it again.

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Rick Fawthrop Avatar
Rick Fawthrop Richard Fawthrop
Langley, WA, USA   USA
What is the availability of a used running engine?

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