Paul
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Jun 23, 2013 22:03:25 GMT
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VR6 Corrado, rough when cold, not particularly down on power, not overheating but using a little water and running hot enough...116C when booted... The results are in...having gone through two dodgy compression testers that just weren't sealing I got my hands on Mel's Gunson.
These results are cold btw - I'm concerned about the discrepancy and the fact that it's all on one side that compression seems to be low...
1 = 160 psi 2 = 205 psi 3 = 160 psi 4 = 205 psi 5 = 150 psi 6 = 195 psi
I double checked the figures, that's defo what they come in at. The top line of cylinders all lower than the bottom...but within 70%...just!
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stealthstylz
Club Retro Rides Member
Posts: 14,853
Club RR Member Number: 174
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Jun 23, 2013 22:38:56 GMT
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It's a bit low on that side, try some oil down the spark plug holes and see if the compression improves.
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ChasR
RR Helper
motivation
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Club RR Member Number: 170
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Jun 23, 2013 22:44:24 GMT
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The high end figures are fine. 195 is not something I would get myself in a twist over either.
160 however on 3 other cylinders may not be great news. Stealthstyle's advice may be the way to go, considering that the VR6 can get weak rings as they age or accrue more miles.
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Paul
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Gotcha - wet test it is...
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bl1300
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Those figures say something is up with those cylinders. Like others have said wet test and see what the results are then.
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Current fleet.
1967 DAF 44 1974 VW Beetle 1303s 1975 Triumph Spitfire MkIV 1988 VW LT45 Beavertail 1998 Volvo V70 2.5 1959 Fordson Dexta
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THe low figures are all on one bank... I smell cam timing I don't really know these motors are these the 12 V with one head and a narrow V
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Contrary to popular opinion, I do have mechanical sympathy, I always feel sorry for the cars I drive.
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Jun 24, 2013 15:48:48 GMT
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it suggest something with that bank. VW made both a 12v and a 24v but yes one head narrow v
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Paul
Posted a lot
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Jun 24, 2013 16:45:40 GMT
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Given that it's the entire bank would that suggest the hg is not the issue?
Not at home to do a wet compression test tonight unfortunately
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ChasR
RR Helper
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Club RR Member Number: 170
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Jun 24, 2013 18:02:24 GMT
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IIRC I am sure that I read somewhere that the first generation of VR6 engines (12V engines) could potentially wear their bores oval after 100k. Certainly the neglected MK3 VR6s near me are quite smokey!
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150psi on the low end isn't that bad, it should still be going 'bang' hard enough. The number 3 cylinder on my old 1500cc Beetle engine was only putting out 70psi!
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hairymel
Club Retro Rides Member
avatar by volksangyl
Posts: 1,081
Club RR Member Number: 207
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Jun 25, 2013 16:27:46 GMT
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while waiting for my pizza to cook i have been playing google mechanic got no idea if i am looking at the right engine or not - so apologies if i have got it wrong! compression test procedure herebank difference suggests a issue but i would think it would be best to avoid taking the engine to bits. i have only just tidied the unit how bad is the issue really? if it goes ok i would be tempted to leave it alone - chasing the megane of despair's engine 'issues' may have a bearing on my attitude though have you checked/changed the thermostat housing and 'crackpipe'? they seem to be a very common coolant failure point.
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whats that burning smell?
oh curse word :-(
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Paul
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Jun 25, 2013 21:04:39 GMT
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I like where your head's at Mel...but I've always been of the mindset 'if it ain't broke then fix it 'til it is'. Did a wet test - instantly compression shot up to 205/200/200 across cylinders 1/3/5 respectively. So I'm tempted to get a new engine Would it be fair to say the piston rings are probably fried?
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hairymel
Club Retro Rides Member
avatar by volksangyl
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Club RR Member Number: 207
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Jun 25, 2013 23:11:33 GMT
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in a vain attempt to guide you away from messing up the unit i can only suggest some form of overfuelling or lack of correct sparking on that bank washing the bores and therefore showing lower compression. otherwise i have tidied my spanner drawer if needed. i also now find that i have a drawer containing approximately a metric gross of jubilee clips and more split pins than any sane person will ever need
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whats that burning smell?
oh curse word :-(
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hairymel
Club Retro Rides Member
avatar by volksangyl
Posts: 1,081
Club RR Member Number: 207
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Jun 25, 2013 23:14:56 GMT
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also have you comp tested it when hot? it may narrow down whether its a cold running issue and also give you the opportunity to acquire some skin grafts to slow down disassembly
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whats that burning smell?
oh curse word :-(
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Paul
Posted a lot
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Hmmm...you may have delayed the inevitable - if only slightly. I'll put her back together and run a warm test. You can owe me a jubilee clip for the 'ghetto' fix I've done on your compression tester. Apparently electrical tape wasn't designed to withstand 200psi. This became clear when the gauge shot off the hose and nearly took my left arm off
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hairymel
Club Retro Rides Member
avatar by volksangyl
Posts: 1,081
Club RR Member Number: 207
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Jun 26, 2013 13:36:51 GMT
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suppose it makes up for all of your stuff that breaks as soon as i look at it
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whats that burning smell?
oh curse word :-(
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Paul
Posted a lot
Posts: 1,911
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Right after much head scratching and Googling it's been suggested that a worn or broken tensioner could put the timing out enough to show poor compression on an entire bank...so it's off with the chains! And gearbox, and bumper, and ancillaries...
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hairymel
Club Retro Rides Member
avatar by volksangyl
Posts: 1,081
Club RR Member Number: 207
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oh - the unit was almost tidy i'll get my coat
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whats that burning smell?
oh curse word :-(
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hairymel
Club Retro Rides Member
avatar by volksangyl
Posts: 1,081
Club RR Member Number: 207
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'if it ain't broke then fix it 'til it is'. Did a wet test - instantly compression shot up to 205/200/200 across cylinders 1/3/5 respectively. so what makes you think timing and not bottom end ?
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whats that burning smell?
oh curse word :-(
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Jun 28, 2013 10:08:36 GMT
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An ABV (Corrado VR6 2.9) is essentially a bored AAA code OBD1 2.8 with a bigger throttle body, so the metal between the bores is thinner and on neglected 2.9's the bores can ovalise (is that even a word!?). Anyhow maybe the the front bank may have been neglected at a service interval and that could have occurred? Only way to check is to crack the cylinder head off and have a looksee. Good luck!
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'73 3.0CS '81 Golf Gti 1.6 '83 Golf 20VT '87 M535i '86 Escort RS Turbo
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