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MG MGB Technical - Engine Project Part 2

This is carried over from the thread "Need help diagnosing this one".

Finally had time to upload new photos of the engine teardown. This is the engine which was running poorly and I suspected a head gasket or similar problem. What I was finding inside was troubling enough to me and many of you kind folk who offered advise that I have torn the engine down further. It isn't looking any better and doesn't seem right for only 11K miles since a full rebuild!

Here's the link to the photos. New pics on page 2.

http://www.lbcnuts.com/engine
Steve Simmons

Steve,

A couple of observations.

Number 2 exhaust looks like it has been overheating, the white carbon deposit is typical of this - could be poor seating or a sticking/bent valve or too tight valve clearance.

The amount and colour of the deposits suggests oil burning or poor quality gas or lots of stop start driving with few long runs.
Chris at Octarine Services

Seems like there's an awful lot of sooty carbon
buildup for such a young engine.

Carbon buildup at the backsides of the valves and
base of the stems will indicate worn valve guides.

If not, then I'd suspect the rings or the crankcase
vent system.
Daniel Wong

What's going on with the rough spot on #3?

Looks like it's been drinking an awful lot of its own coolant, oil and goodness knows what else.

Does anyone else think that the pistons look a bit small?

ttfn,
--
Olly
Oliver Stephenson

Steve you take some great pictures. I've not opened up two many engines but, I find it hard to believe that this engine ever ran fine since rebuild or since you brought it out of storage. If I were to make a wild guess and a wild guess is all I'm qualified to make, I would guess the car was stored for several years with only water in the system and no AF. I'm hoping money has no influence at this point so you can build the engine you want.


Good luck
Kevin Pearce

Kevin, the car was stored for a few years and brought back into normal use about three years ago, but there was a 50/50 water & antifreeze mix in it. It ran really well until just a few months ago.

Chris, I do a lot of stop and go in traffic but I also give it a lot of long runs at speeds I don't care to admit. ;)

Oliver, I do remember the mechanic telling me he was using oversized rings to save the cost of new pistons. He told me it would be no problem and I believe him because he (before he retired) was one of the most knowlegable people I've ever known regarding British engines. But I think he must have let his apprentice rebuild this one. :(
Steve Simmons

BTW Kevin, I'm in Kansas City right now. :)
Steve Simmons

Oversized rings with standard pistons?

I myself would call that a bodge. Your mileage may vary but I doubt you'd keep good compression for very long with that.

I think full disassembly is in order, although with all the corrosion even the block might be a write-off.

Good luck,
--
Olly
Oliver Stephenson

Well, not necessarily oversized rings but the largest rings allowed for those pistons.

Anyone have a recommendation for a machinist familiar with B engine blocks in the So Cal area?
Steve Simmons

While he's not a machinist, I can heartily recommend Maul's Garage in Huntington Beach
greg fast

May I ask what air filter covers they are?
Stefan Carlton 1

Steve,
Damn, if your that close I'd better watch what I say! My age prevents me from using my gladiator skills. I'm sure your flying but if you were driving you might drive right by me on your way home.

Kevin
Kevin Pearce

I reckon that gasket's failed. You can see dry, dark patches between the cylinder bead and the bolt holes and coolant passages on all cylinders, which I'm guessing are made by exhaust gasses.

Steve, did it overhead easily on load or blow its coolant out all the time?

ttfn,
--
Olly
Oliver Stephenson

Kevin, indeed I am flying. But no worries anyway because I don't have very good gladiator skills either.

Oliver, it did not overheat easily. In fact it only began to show signs of overheating twice in heavy traffic and it didn't get that bad, just a bit of rough running which I attributed to the carbs getting too hot. It didn't typically lose coolant either.

Stefan, I have the original, stock air filters that came on the car from the factory.

Greg, I'd love to get ahold of you off the BBS about a couple things. If you have the time, email me if you get the chance. :)
Steve Simmons

This thread was discussed between 17/09/2004 and 18/09/2004

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.