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what causes low compression

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Old 26-04-2013, 02:32 PM
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kurdt5
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Default what causes low compression

Just curious what causes engine compression problems?
Old 26-04-2013, 02:47 PM
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LHD220Turbo
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worn ring, worn valves or fucked head gasket basically

Last edited by LHD220Turbo; 26-04-2013 at 02:48 PM.
Old 26-04-2013, 03:43 PM
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Originally Posted by LHD220Turbo
worn ring, worn valves or fucked head gasket basically
what if its a new engine? could one of these still happen?
Old 26-04-2013, 03:54 PM
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Jacked up hydraulic lifter? What engine you got a problem on
Old 26-04-2013, 05:25 PM
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Originally Posted by kurdt5
what if its a new engine? could one of these still happen?
then you need to give a bit more info mate

new engine in a new car?

or just a newly built engine? who built the engine? what was changed? what symptoms have you got, did you get the compression issue as soon as it started or after a period of time?
Old 26-04-2013, 05:54 PM
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Originally Posted by LHD220Turbo
then you need to give a bit more info mate

new engine in a new car?

or just a newly built engine? who built the engine? what was changed? what symptoms have you got, did you get the compression issue as soon as it started or after a period of time?
Series 1 Rs turbo running OFAB EFI.
Rebuilt car and engine by Vroom Ptshhhh.

https://passionford.com/forum/pictur...-rs-turbo.html

Car was fine, tuned at Read Performance and ran well. Last week mot was up but needed a bearing so the mechanic collected the car did the work and mot.
But when it came back it sounded like a Subaru, exhaust stutterring/popping.
I changed plugs, leads and coil...tightened hoses and still my S1 sounds f**ked from its time the mechanic took it for its MOT, they also turned the boost down for some unknown reason.
Engine has only done 1300 miles from new and was fine until the car was returned.
Old 26-04-2013, 05:59 PM
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Originally Posted by kurdt5
Series 1 Rs turbo running OFAB EFI.
Rebuilt car and engine by Vroom Ptshhhh.

https://passionford.com/forum/pictur...-rs-turbo.html

Car was fine, tuned at Read Performance and ran well. Last week mot was up but needed a bearing so the mechanic collected the car did the work and mot.
But when it came back it sounded like a Subaru, exhaust stutterring/popping.
I changed plugs, leads and coil...tightened hoses and still my S1 sounds f**ked from its time the mechanic took it for its MOT, they also turned the boost down for some unknown reason.
Engine has only done 1300 miles from new and was fine until the car was returned.
ohh dear, do you know the mot man/ garage well

sounds like a familiar story whereby the garage has collected the car, ranted the bollocks out of it, caused a problem and then tried to hide their tracks by turning down the boost. call me suspicious if you like........

what did the mot man say when you collected it and it wasnt running right?
Old 26-04-2013, 06:07 PM
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He dropped the car off and said all mot'd new bearing no advisories.
When he went i started her up and reversed and noticed as soon as i touched the accelerater it sounded like a subaru....i took it around the block and sounded awful.

Rang the guy who just said when he drove it the car lurched ect from the boost cut off so they turned the boost down, they couldnt tell me what bar its running on or anything.
I cant prove he ragged it if I went to VOSA but if the cut off kicked in then he was booting it.

I have a mechanic coming tomorrow who works with Turbo's, he said if I've changed the coil, leads and plugs then a compresson test should help find the source.
I just havent the cash to spend on a big job, and Dave built the car to a great standard and now some tosser has messed all that work up.
Old 26-04-2013, 06:07 PM
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Have you actually checked the compression?
Old 26-04-2013, 06:10 PM
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Originally Posted by Kitchen Devil
Have you actually checked the compression?
Have someone from Advanced Engine Dynamics coming to my house tomorrow, There are no garages around here to trust.
Last garage burnt my S2 out then wanted me to foot the bill.
Old 26-04-2013, 07:21 PM
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Originally Posted by LHD220Turbo
ohh dear, do you know the mot man/ garage well

sounds like a familiar story whereby the garage has collected the car, ranted the bollocks out of it, caused a problem and then tried to hide their tracks by turning down the boost. call me suspicious if you like........

what did the mot man say when you collected it and it wasnt running right?
Exactly what I said on his other thread
Old 26-04-2013, 07:32 PM
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Just a little thing I had on a s2 rst I had

under the rockers there is a little shim and if it is not there it lifts the valves a little so you get low or no comp

Worth looking

http://www.burtonpower.com/washer-ro...cvh-cv233.html
This is the part I'm on about
Old 26-04-2013, 07:43 PM
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Also I had something like that on another rst I had

Got the clutch changed and as the bloke that done the work put it back together he clipped the air charge temp sensor wiring between the block and gearbox so as I drove it and it cannon boost it piped and banged and ran like shit.
Old 26-04-2013, 09:28 PM
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Sounds like they have killed it mate and as said turning down the boost to try and cover there backs. You need to go and see them with the car the way it is and demand they sort it out otherwise VOSA will be involved. They might back down and fix it or you will have a battle on your hands because its your word against there's' but on the plus side if the garage has a bad back ground VOSA might step in and sort something out.
Old 26-04-2013, 09:57 PM
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surely if it was running rough it would have never passed the mot test
Old 26-04-2013, 10:04 PM
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LHD220Turbo
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its very common for this to happen, about 10 years ago an MOT tester an apprentice i knew decided to take a customers porsche out for a spin after an MOT....they wrote the thing off
Old 26-04-2013, 10:20 PM
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oh dear, sounds like the driver has fucked it, if it was fine before then a massive coincidence no?

a guy i worked with had his car in a halfords auto thing a few years back, e46 m3...

the police came knocking one night asking why he was on cctv driving like a complete cunt through chippenham high street...

when he expained the car had been having work done for 2 days and wouldnt be ready for him till the next day, you can probably guess he wasnt best pleased!
Old 26-04-2013, 10:49 PM
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I reckon it's burnt a valve
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