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Right, I've done a compression test and it doesn't look good.
Cylinder 1 = 150psi
Cylinder 2 = 190psi
Cylinder 3 = 220psi
Cylinder 4 = 110psi
Haynes doesn't have a figure in there and I haven't gone on Autodata yet, but according to a thread I found on a fiat forum the compression should be around 175psi. Hmmm...
There is a bit of smoke coming from the crankcase breather pipe too.
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They're very uneven, certainly. I'd expect to see 160-190, depending on the age and condition of the engine. Much less than 120 is going to start cauing running issues.
For example, Hardcore's Mercedes engine had 5 cylinders at 160psi and one at 75 - it was running on 5, using lots of oil, and when you took the oil filler off it blew smoke rings in time with the misfire...
2 quick questions: 1) Did you hold the throttle wide open while cranking, with all the plugs out? and 2) have you done a wet test? (Wet test = a little oil - maybe 10ml - down each bore in turn just before testing that bore. This improves the seal of the piston rings, so the compression pressure will rise a bit. If it rises a lot from a low dry reading, it points to worn rings/bores. If it doesn't rise much it points to HG/valve sealing issues.)
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ChasR
RR Helper
motivation
Posts: 10,309
Club RR Member Number: 170
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Punto firing on 3?ChasR
@chasr
Club Retro Rides Member 170
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I was about to say, do a wet test.
If it is the Gunsons tester from Halfords the figures are consistent on a good engine but nothing more. As an example with mine a friend's Nissan S12 Turbo dod 180PSi on all cylinders, my old 400,000 mile Mondeo did 240 on each cylinder (it was a smooth runner to be fair!), and a mate's car (same type of car) did between 120-250. A large error I admit but with compression, unless the figures are low I have been led to believe that consistency counts, rather than the actual figure.
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They're very uneven, certainly. I'd expect to see 160-190, depending on the age and condition of the engine. Much less than 120 is going to start cauing running issues. For example, Hardcore's Mercedes engine had 5 cylinders at 160psi and one at 75 - it was running on 5, using lots of oil, and when you took the oil filler off it blew smoke rings in time with the misfire... 2 quick questions: 1) Did you hold the throttle wide open while cranking, with all the plugs out? and 2) have you done a wet test? (Wet test = a little oil - maybe 10ml - down each bore in turn just before testing that bore. This improves the seal of the piston rings, so the compression pressure will rise a bit. If it rises a lot from a low dry reading, it points to worn rings/bores. If it doesn't rise much it points to HG/valve sealing issues.) I was about to say, do a wet test. If it is the Gunsons tester from Halfords the figures are consistent on a good engine but nothing more. As an example with mine a friend's Nissan S12 Turbo dod 180PSi on all cylinders, my old 400,000 mile Mondeo did 240 on each cylinder (it was a smooth runner to be fair!), and a mate's car (same type of car) did between 120-250. A large error I admit but with compression, unless the figures are low I have been led to believe that consistency counts, rather than the actual figure. Yep, had the throttle open but the instructions on the compression guage box said just remove one plug at a time, so that's what I did. Does it cause much of a differance? Didn't get a chance to do a wet test as I had to get to the nursury to get Mini MiniDan. Will try tomorrow/Sat. One thing I did do that I forgot to say, I listened to the exhaust as you said jrevillug. While it was idling the exhaust sounded smooth and there was no miss at all. Either tomorrow or Saturday, whenever I get the chance, I will also double check the timing. I can't help but think there might be a problem there. |
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ChasR
RR Helper
motivation
Posts: 10,309
Club RR Member Number: 170
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Punto firing on 3?ChasR
@chasr
Club Retro Rides Member 170
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IME taking one plug out at a time does not make much difference but it can help in not getting rubbish down the other cylinders (which at the best of times is easier said than done).
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In theory if you have one cylinder with no compression, the engine will accelerate slightly before the next compression stroke, so the next compression number will be a bit higher.
IME, you get more consistant and comparable readings with no plugs in.
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Does yours have the little ecu on the back of the engine these all ways go faulty and cause a missfire you can get them from yhe localparts shop and don/t nead coding in with a diagnostic machine hopes this helps
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Won't help the low compression though will it?
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309jazzpanda
Part of things
so its just my pug thats rotten?
Posts: 92
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right i'd check your injectors are getting a feed with an led, that way it rules out ecu and you know its mechanical. as easy as it is no point in whipping a head off to find all is well. when you had the head off what condition were the bores like? i've had a few puntos come in with head gasket and once stripped the bottom end toasted. I've even had one that got so hot an exhaust was stuck midway open
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1990 309 "the pig"
1993 205 gtx "mummra"
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the main reason for removing all the spark plugs to compression test is if the head gasket has blown between cylinders you could get a compression reading from the next cylinder , whereas if the plugs are all out it will only be reading from whatever compression is in the cylinder being tested .
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To be quite honest .. i don't think it soundslike your problem is compression related .. I could be completely wrong but here goes ive seen this quite a few times .. you said the cam looks burnt .. is it dry ?? Because ive seen a few people put the head gasket on upside down .. its very easily done on this engine .. and everything still matches up .. except the OIL FEED TO THE CAM !!!!!!! Sorry not really what you want to hear but it would explain the noise and the lack of power .. start the engine with the cam cover off .. it should spray oil everywhere .. good news is its not a bad hg to do again and if it hasnt actually seized the cam should be ok .. hope this helps good luck with it.
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its not a rust hole its air conditioning
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Had 20mins free earlier. Didn't have time to do much but... To be quite honest .. I don't think it soundslike your problem is compression related .. I could be completely wrong but here goes ive seen this quite a few times .. you said the cam looks burnt .. is it dry ?? Because ive seen a few people put the head gasket on upside down .. its very easily done on this engine .. and everything still matches up .. except the OIL FEED TO THE CAM !!!!!!! Sorry not really what you want to hear but it would explain the noise and the lack of power .. start the engine with the cam cover off .. it should spray oil everywhere .. good news is its not a bad hg to do again and if it hasnt actually seized the cam should be ok .. hope this helps good luck with it. Whipped the rocker cover off and started it up and it was spraying oil everywhere. Thanks for the suggestion  I was dropping a brick that I had put it on the wrong way. |
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No worries sorry for freakin you out !! hope you figure out whats wrong with It soon !!
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its not a rust hole its air conditioning
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I was dropping a brick that I had put it on the wrong way.