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roughly what compression figure on my pinto
omega0684 - 25/5/09 at 07:17 PM

i have a fairly old compression tester that measures in kpa and psi,

can anyone tell me roughly what figures i should be looking for on a 2.1 pinto when i carry out a compression test or is it a case of as long as they are all roughly the same?

cheers

Mark G - 25/5/09 at 07:23 PM

haynes manual says between 10-13bar for a 2.0 engine. Can't be much different.

Conversion = roughly 140 - 170 psi

Doesn't matter too much if it falls a little short but as you said you want them to be pretty uniformed across the cylinders.

omega0684 - 25/5/09 at 07:32 PM

i think my compression tested has had it then. im getting 100 psi on 1,2 & 4 and 160-170 on 3, just started the car and it sat there ticking over quite happily

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ReMan - 25/5/09 at 07:37 PM

I would say thats a problem with the engine not the tester

]|How did you get it to start? What was amiss?

omega0684 - 25/5/09 at 07:43 PM

put some oil in it and turned the key! stared first time!

ReMan - 25/5/09 at 07:51 PM

Excellent,
so you'll know how to stop that happening agian

omega0684 - 25/5/09 at 07:56 PM

you got me worried now though, y are the cylinders only giving 100 psi on cylinders 1,2, & 4?

Mark G - 25/5/09 at 07:57 PM

possibly worn rings, by putting oil in the bores you're temporarily sealing them up and getting compression.

omega0684 - 25/5/09 at 08:03 PM

surely they should wear as a fairly consistant rate, the engine has only done about 15k since it was rebuilt

Guinness - 25/5/09 at 09:04 PM

Compression tests should be done with the engine fully warm, so you may be getting readings on the low side.

Also, you have to have the throttles wide open during cranking, to let the air in.

You have R1 throtte bodies, so a quick visual check that all the butterflys are opening fully and in sync would be worthwhile.

Good luck

Mike

ReMan - 25/5/09 at 09:48 PM

quote:
Originally posted by omega0684
you got me worried now though, y are the cylinders only giving 100 psi on cylinders 1,2, & 4?


Or why is 3 giving a high reading?

I'm sure you've measured them more than once, so as siaid, your looking for consistent readings across all 4, more important than the actual reading, so 1 sitting out like this is not good IMHO

Might be an over oily bore, could even be valve seals.
Might be worth trying a squirt of oil in one of the low ones, see if that brings it up?

just a thought, does your mega thingy wotsit go into some sort of panic mode if it detects over temp engine?
I'd still swear it was not fueling that was stopping it from re-starting...

mark chandler - 25/5/09 at 10:11 PM

Another clue to good or bad is how much the revs drop if you kill a cylinder.

Engine idling, knock the ignition leads off in turn to see the effect, if all cylinders are the same the revs will drop by the same amount assuming everything else is balanced.