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MG MGA - Crank shaft disaster!!
|Hi chaps, last week, whilst on my way to the Silverstone Classic, my oil pressure started to drop from the usual 60, down to 40 - for no reason. I stopped at the next services after a couple of miles, and as I was parking, the guage registered zero - so I quickly switched off, at which point the temperature guage went from 190 to it's max of 240f. I was trailored to Silverstone, (enjoyed a great weekend) and then trailored home again (thanks RAC!!) My mechanic has now taken the engine out and I need a new crank. My problem is wondering what caused it in the first place - especially the rise in temperature. |
When the engine was cold during the Silverstone weekend, I checked oil and water levels and they were both ok. I also started the engine, and at cold tickover got 50 pounds pressure. I drove it for a couple of miles, and then heard knocking from the engine. The car had an oil and filter change a month ago - and until last week was running as sweet as a nut.
I'm reluctant to have a new chank, oil pump, drain on my bank balance etc - until I know what the likely cause was, in case it happens again - anybody got any ideas??
|D J Hill|
|Sorry to hear about this but one thing you don't mention is what type of engine it is?|
|I had a customers MGA in for new bushings in front suspension. On the road test I watched the oil pressure go from 60 to zero in less than 1/2 mile. Car had been driven from Texas to Sebring for a GOF without any problems. I had to replace crankshaft as it had spun two rod brgs and was seriously blue from overheating.|
|Why do you need a new crankshaft, is it broken in half or has a bearing run scoring the journal below that that can be corrected by grinding?|
You don't have much choice in spending the money if the crank is cactus. A rebuilt engine by a reputable engine builder will get you back on the road for another few years/100,000 kms. They will insure lubrication, alignment and clearances are correct. These type of failures do happen to 60 year old cars/engines.
|The temperature rise after switching off is totally normal. Usually people don't notice because the rarely sit in the car looking at the gauge after a hard or long drive.|
Sounds like the big end(s) went fairly quickly and I don't know how common that is, but an examination of the engine parts normally tells all.
A couple of years ago there was a case in the US where one of the (other MGA) forum guys had a felt oil filter disintegrate, trashing his engine. Again pictures of the stripped engine or a better explanation from the mechanic are required.
These engines are as bulletproof as any engine, more so. A properly rebuilt engine is good for 10s if not 100s of thousands of trouble free miles.
|Sounds like a spun rod bearing....Hey at least you don't need a new engine block!|
|As Neil has indicated the engine temp goes up because the water pump is no longer circulating cooled water.|
This thread was discussed between 02/08/2014 and 03/08/2014
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