Been cheated on a car rebuild - where do I stand please?
Discussion
Interesting comments chaps. There is a possibility the engine was built in- correctly. Again,I'm not entirely convinced that one would rebuild an engine but continue to use tired old parts on it.
Good point regarding consistent wear across all cylinders. This could point to a poor build or defect perhaps.
I have seen very poorly engine have huge differences across the cylinders.
I'll aim.to get the car on the rollers this week and report back.
Good point regarding consistent wear across all cylinders. This could point to a poor build or defect perhaps.
I have seen very poorly engine have huge differences across the cylinders.
I'll aim.to get the car on the rollers this week and report back.
Worth pointing out that there are a bunch of things that can affect compression ratio, and only a few of them relate to an "old tired engine"
Knackered engine:
Piston ring or bore wear/damage - scored or damaged bores, and worn rings let gases escape past the ring.
Valve seating - valves failing to seat allow pressure to escape into to the valve ports.
Errors in design or assembly:
Bore/Ring mismatch : e.g. your engine has been overbored +65 thou, but only +60 rings were fitted.
Head gasket thickness : Thicker head gasket changes the ratio between swept volume and combustion chamber volume.
Head vs. Block mismatch : Example - putting some Triumph 2.5 heads on a 2-litre block *drops* compression ratio because combustion chamber size in head is larger.
Camshaft profile : Hairy race cams with big overlaps will give lower compression ratios as measured by a normal test. http://www.badasscars.com/index.cfm/page/ptype=pro...
Cam timing - if the valves aren't open/shut at the right time, compression is lost
Short pistons fitted : pistons don't reach deck of the block at TDC
Other possibilities:
Rings not yet bedded in fully : Until the rings wear to match the bore profile, some compression will be lost.
Operator error : e.g. Throttles not held open during test
Measuring error : Faulty gauge?
And I'm sure there are others...
Knackered engine:
Piston ring or bore wear/damage - scored or damaged bores, and worn rings let gases escape past the ring.
Valve seating - valves failing to seat allow pressure to escape into to the valve ports.
Errors in design or assembly:
Bore/Ring mismatch : e.g. your engine has been overbored +65 thou, but only +60 rings were fitted.
Head gasket thickness : Thicker head gasket changes the ratio between swept volume and combustion chamber volume.
Head vs. Block mismatch : Example - putting some Triumph 2.5 heads on a 2-litre block *drops* compression ratio because combustion chamber size in head is larger.
Camshaft profile : Hairy race cams with big overlaps will give lower compression ratios as measured by a normal test. http://www.badasscars.com/index.cfm/page/ptype=pro...
Cam timing - if the valves aren't open/shut at the right time, compression is lost
Short pistons fitted : pistons don't reach deck of the block at TDC
Other possibilities:
Rings not yet bedded in fully : Until the rings wear to match the bore profile, some compression will be lost.
Operator error : e.g. Throttles not held open during test
Measuring error : Faulty gauge?
And I'm sure there are others...
informative post Silentbrown.
Just a small update chaps. We seem to have got the car running significantly better then when I got it.
There was a sensor that was not connected that has now been rectified [ I can't recall which one but will find out for those interested]. Also the timing has now be done to perfection and that has made a big difference.
Although I am yet to drive the car, my mechanic comments on a marked improvement.
There were a few other tweaks done here and there to get the engine running smoothly. It is now less lumpy and more eager high in the rev range.
Above 4000rpm where the car used to feel flat and tail off the power the car now picks up much better. I am sure the compression has improved with perfecting the timing too. As yet don't know exact figures but I've not focused on this so much - rather we have aimed to get the car running better.
Slightly annoying that again I have had to pay for all this to be done, but I feel happier that the car is at least driveable.
Maybe next up is a new set of plug leads as the current ones are on their last legs - again this may help with better running as suggested earlier in the thread.
Also putting some miles on the car could help -especially if it has been sat around for some time. I may have only done 20 miles in the car max.
Putting on a few hundred will hopefully help. I suspect the engine has just sat around for some time prior to installation. Just to be clear this is not a 'fresh' rebuild and does not require running in...
I'm sure most on here have worked out this is an M car - hence me emphasizing that the performance should be pretty good. I've purposely not gone into too much detail until I am totally happy with what I have paid for and what I have received in the end.
I should be getting the car back from my local tuner tomorrow. I'll post back once I have driven it.
Again - thanks for all those who have posted. It's been very helpful and I have learn't a lot.
Just a small update chaps. We seem to have got the car running significantly better then when I got it.
There was a sensor that was not connected that has now been rectified [ I can't recall which one but will find out for those interested]. Also the timing has now be done to perfection and that has made a big difference.
Although I am yet to drive the car, my mechanic comments on a marked improvement.
There were a few other tweaks done here and there to get the engine running smoothly. It is now less lumpy and more eager high in the rev range.
Above 4000rpm where the car used to feel flat and tail off the power the car now picks up much better. I am sure the compression has improved with perfecting the timing too. As yet don't know exact figures but I've not focused on this so much - rather we have aimed to get the car running better.
Slightly annoying that again I have had to pay for all this to be done, but I feel happier that the car is at least driveable.
Maybe next up is a new set of plug leads as the current ones are on their last legs - again this may help with better running as suggested earlier in the thread.
Also putting some miles on the car could help -especially if it has been sat around for some time. I may have only done 20 miles in the car max.
Putting on a few hundred will hopefully help. I suspect the engine has just sat around for some time prior to installation. Just to be clear this is not a 'fresh' rebuild and does not require running in...
I'm sure most on here have worked out this is an M car - hence me emphasizing that the performance should be pretty good. I've purposely not gone into too much detail until I am totally happy with what I have paid for and what I have received in the end.
I should be getting the car back from my local tuner tomorrow. I'll post back once I have driven it.
Again - thanks for all those who have posted. It's been very helpful and I have learn't a lot.
silentbrown said:
If it's an E28 I shall be envious, regardless of how lumpy it is at present.
Not an e28, judging by old posts, but all M-cars are items to be admired and cherished.Just my personal opinion, of course, but I can't see that you'd get much of an engine for the price paid. Which is why it was so important to know the type of car. All the same, glad to hear that it's on the mend.
A low compression test reading can also be caused by a poorly battery or starter motor. Or not realising that you're supposed to take all of the plugs out. There are probably other reasons - that's why it's difficult to compare absolute values and you generally compare one cylinder to another. Leakdown tests have their own set of issues as well.
BertBert said:
I'm confused. I thought you were getting the original supplier to sort it out. If you are now using an alternative (at your own cost), won't this compromise your argument with the people who did all this for you?
Bert
you're right to be confused. I have spoken to the original supplier and he has agreed to take the car back. However, the problem with that was that the original supplier and I were in complete disagreement. Bert
What he thinks is fine and healthy - I do not. If this ordeal ended up in court I would have had to demonstrate that I gave the original supplier the chance to rectify the problem.
The fact that they let the car out of their workshop in a poor state did not inspire me with confidence. The car has been with my local man for over two weeks and we have made some noticeable improvements.
I wasn't keen to go down the small claims court route. However, I felt that may well have come about if I could not improve the car.
If my local man could get the car to drive well then I would settle for that - even if I have to pay extra to achieve that.
Dr Imran T said:
BertBert said:
I'm confused. I thought you were getting the original supplier to sort it out. If you are now using an alternative (at your own cost), won't this compromise your argument with the people who did all this for you?
Bert
you're right to be confused. I have spoken to the original supplier and he has agreed to take the car back. However, the problem with that was that the original supplier and I were in complete disagreement. Bert
What he thinks is fine and healthy - I do not. If this ordeal ended up in court I would have had to demonstrate that I gave the original supplier the chance to rectify the problem.
The fact that they let the car out of their workshop in a poor state did not inspire me with confidence. The car has been with my local man for over two weeks and we have made some noticeable improvements.
I wasn't keen to go down the small claims court route. However, I felt that may well have come about if I could not improve the car.
If my local man could get the car to drive well then I would settle for that - even if I have to pay extra to achieve that.
It matters not what you think of them as a company, but you can't 'fix' it and then claim for damages afterwards.
^^ I'm aware of that - I can still get the initial report from my local man. It would simply state that customer brought car in due to poor running.
If it still runs awful then it is going to perhaps harder to claim but I'd still be able to document what I have done.
Obv. any further work that I have done I would not claim for..
If it still runs awful then it is going to perhaps harder to claim but I'd still be able to document what I have done.
Obv. any further work that I have done I would not claim for..
Ahh yes a familiar and hateful place to be. When you are pretty sure that the original guys won't make any better job of it. Time to cut losses and get a car that runs at least reasonably well.
I'm not asking for the name, nor snooping, but do the people you used previously have a strong and good market reputation? It's really galling when it goes wrong with people who are reputed to go a good job. In the world of old 911s where I dabble it's amazing how many people have tales of disputes with suppliers of otherwise good renown. I've certainly got one.
Bert
I'm not asking for the name, nor snooping, but do the people you used previously have a strong and good market reputation? It's really galling when it goes wrong with people who are reputed to go a good job. In the world of old 911s where I dabble it's amazing how many people have tales of disputes with suppliers of otherwise good renown. I've certainly got one.
Bert
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