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strange compression results/updated test :(


mellonman

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i will start off and let everyone know whats happend

my hybrid turbos let go and sent oil and god know what round the engine,

so i stripped of the turbos to access damaged and iit was bad, so thought i would do a compression test to see if i could find any clear troubles,

 

the problem i have is that the cyclinders are full of oil and i clearly see it in some of them

 

1=219

2=205

3=204

4=195

5=192

6=200

 

 

now these results seem way high to my understanding but do make sence as there full of oil and number 1 would of got the most. does anyone know how to clear the oil so i can get a more clear reading or is it head off job

Edited by mellonman (see edit history)
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i would love to do the leak down test but i cant move it,http://www.mkivsupra.net/vbb/showthread.php?256686-leakdown-test-would-this-work-and-understanding

would this work i will see if my friend can get hold of a bore scope.

is there a way i can clear the oil from the pistons with no turbos attacted

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its been sat since saturday but i can still clearly see oil on the pistons and on the plugs when i took them out. i mean when i took the plugs off they was coated in oil. could i spay carb cleaner down into the cylider to fin out the oil and then suck that out or let it drain off

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No, the carb cleaner will go straight past the rings and into the sump. There may still be a coating of oil on the plugs, but as long as its not swimming in the stuff, you should be fine. As mentioned above, spin it over on the starter with the plugs out, that will get rid of it :)

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But cover the top of the engine with a towel or something unless you want oil blasted all over the place lol.

 

I assumed the chap had some common sense and didn't want to appear patronizing by saying that :p

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well i will give it ago again later,to see it that no1 comes down abit if that oil has a chance to drian off. im gutted i cant really do a leak down test as i dont have the tool or means to move the car, is there a mobile service that could do it anyone know of i can get hold of a small compressor?

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okay so after another day and some turning over to clear what was left of some oil, i redone the compression tests the results as follows

 

1=200

2=195

3=199

4=193

5=185

6=200

 

so as 5 was down i done it again and it dropped by another 5psi so i thought what the hell done it again and it dropped again by another 5psi till i was at 175 and then stayed at 175 so i put some oil down the hole to check to see if its the rings and tested again and it shot back up to 200.

 

 

so what to do with it all does it need a rebuild?

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Sounds like the rings on cyl 5 are worn. Personally, I wouldn't rebuild it. How many miles are on the engine? What are your plans? Staying TT or going single? I've seen some of our engines win races time and time again with one cylinder down on compression by ~20%.

 

Changing the rings would mean dropping the sump, unbolting the rod and pushing the lot out of the top. Not sure how much a set of rings are, however for my V8, oversized aftermarket rings were 190 quid for a set.

 

Edit: Without wanting to state the obvious, if your taking the head off, might as well change the belts, water pump etc etc.

Edited by ugp (see edit history)
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I wouldn't take too much notice of compression test results, especially after it's had a drink of oil. Either get a leakdown test done or toss a coin. The results don't look terrible, it should at least run ;) I use a diving bottle full of compressed air at 207 bar and a regulator to do stuff like that away from a compressor, but I ain't bringing it to Kent, sorry ;)

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I wouldn't take too much notice of compression test results, especially after it's had a drink of oil. Either get a leakdown test done or toss a coin. The results don't look terrible, it should at least run ;) I use a diving bottle full of compressed air at 207 bar and a regulator to do stuff like that away from a compressor, but I ain't bringing it to Kent, sorry ;)

 

i do so love your engenuity chris, looks like i will just do the bodge leak down test and see whats what.it did run okay before the turbos let go there is that and the bits of turbo didnt do any damage and its just worn rings which i would expect from a car that has done 140,000 miles. i was going to go small single as there was a setup going cheap. that worked out cheaper then doing hybrids again that might go bang again next year.

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140k? They aren't bad results at all. Infact, I would be over the moon with them! Whack the bloody single on it and drive the thing :p

 

really? i still think something is wrong why are they so high results,the book said 0.9 - 12 bar i was getting nearly 14 but that might be cos the oil still sitting on the rings and i guess as im still getting the high results 3 days later the rings must be good to even have the oil still there :D .

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