Broken crankshaft on TVR ( rover ) V8
Discussion
Suffered Hydro locked engine recently when a new injector suck open and filled a cylinder with fuel. After replacing the injectors all appeared to be well again but after just a few miles ( about 10 ) the crank snapped. What is the collective opinion on this ? Would that just be unlucky coincidence or was it damaged by the abrupt halt. It seems the con rod survived the lock up and opinion is that this would have bent before the crank. Engine has 41k on it and ran fine before.
Comments appreciated.
Comments appreciated.
I know of a rover which snapped it's crank at idle. The stroker engines (well some of them) don't have enough beef between the counterweights and the pin ends.
A custom crank would be expected to have more material in this area as by stroking you are moving the pin away from the crank centre thus redusing the overlap. This weakens the crank. To counter this you either use bigger journals, add extra material, add a web or do all of this
Boosted.
A custom crank would be expected to have more material in this area as by stroking you are moving the pin away from the crank centre thus redusing the overlap. This weakens the crank. To counter this you either use bigger journals, add extra material, add a web or do all of this
Boosted.
Wow, I'm amazed that a normal injector was able to flow enough fuel to hydraulically lock the engine while it was running. But if this has happened I think the risk of machanical damage is quite high, and it's entirely credible that weakened components that were not checked or replaced might fail shortly afterwards.
I was only aware of the Hydro Lock when cranking it on the starter so fairly low RPM. Happened three times, third time stripped (I think) the starter as it then spun without turning the engine. Don’t know if it was meeting fluid in the cylinder prior to that, it did have a very lumpy idle.
Would assume that the weakening damage to the crank was done first time, and that it just went afterwards will accelerating. Standard a crank needs to handle a lot of vibration and intermittent loads at different positions. Bad luck, but replacing it should not be too difficult and too expensive. Standard crank was good enough for group A rover SD1 racers.
Rob
Rob
350zwelgje said:
Rob (v8 racing) should be able to help for example (and others of course). And would expect around 300-400 pounds in parts maximum for crack, bearings and a few gaskets.
Rob
The problem stevie is going to have is the 500 crank is one of its own so unfortunetly the 300-400 budget is way out, even an after market 90mm wont fit due to the counterbalances being too tall, and if you grind enough off to clear the piston skirt there's not enough left to balance it, unfortunetly it has to be a new 500 crank which the price mentioned earlier £900 is about right, or a complete new short engine of a different configuration
It went bang when lifting off at about 4000rpm from a good hard squirt to change from second to third. Oil light came on but I didn’t realize what had happened immediately, I thought had just died but then realized it was still running but pressure was zero. I guess it ran for about 30 seconds or so after the bang before I could pull up. After that it was briefly started twice. Have to say I can’t figure how it could run and re start at all with a broken crank.
Do we think it is likely that lots of other bits will have been chewed up or will it be OK with a new crank and bearings. I am wondering if at this stage the best bet would be to go for a complete guaranteed engine from one of the specialist builders. That way at least I would get the performance gain that I was looking for to start with and not be constantly fretting that something else will break as a result.
Do we think it is likely that lots of other bits will have been chewed up or will it be OK with a new crank and bearings. I am wondering if at this stage the best bet would be to go for a complete guaranteed engine from one of the specialist builders. That way at least I would get the performance gain that I was looking for to start with and not be constantly fretting that something else will break as a result.
On many engines there will be an oil-way diagonally through a main bearing journal. The crack follows that so the two ends will still drive.
Drove a mini from the south coast back to Surrey with the rear journal broken. It maintained drive provided you rested your foot on the clutch to press the break together.
Steve
Drove a mini from the south coast back to Surrey with the rear journal broken. It maintained drive provided you rested your foot on the clutch to press the break together.
Steve
GreenV8S said:
Have to say I can’t figure how it could run and re start at all with a broken crank.
I guess if the broken ends were still more or less intact they could still engage enough to turn the far end of the crank.
V8s is correct as usualy, because they dont shear straight they will still engage, out of interest is the engine stripped yet, or are you just guessing the crank has snapped? its just it wouldnt normally lose all its oil pressure?
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