smart51
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 posted on 11/11/05 at 05:00 PM |
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compression test - update: low compression
How do I do a compression test? Is there a cheap tester that I can buy?
I have tried a number of local garages around here and none of them want to know. The car garages because it is bike engined and the bike garages
beacuse it is a car. I'll di it myself if I can.
[Edited on 12-11-2005 by smart51]
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britishtrident
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| posted on 11/11/05 at 05:21 PM |
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I bought one off this ebay seller a couple of weeks back -- great quality & price and the quickest delivery ever, he also sells some other nice
tols.
http://cgi.ebay.co.uk/BRAND-NEW-COMPRESSION-TESTER_W0QQitemZ8013463510QQcategoryZ30921QQtcZphotoQQcmdZViewItem
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zzrpowerd-locost
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| posted on 11/11/05 at 06:46 PM |
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if its only a compression test, why dont any garages want to know??
An engine is an engine after all! Same test whatever the engine! Remove spark plug and screw in compression tester!
All cylinders should more or less be the same compression
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britishtrident
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| posted on 11/11/05 at 07:15 PM |
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Thinking about it many car style testers don't fittings for 10 and 12 mm plug threads.
One with a rubber cone push/hold on fitting like this one might be best
http://cgi.ebay.co.uk/PRO-TUNE-COMPRESSION-TESTER-KIT_W0QQitemZ8013747854QQcategoryZ30921QQrdZ1QQcmdZViewItem
[Edited on 11/11/05 by britishtrident]
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millenniumtree
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| posted on 11/11/05 at 08:49 PM |
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I'm currently in the process of doing the head gasket in my civic. One of the goals in doing this, was to improve or even out compression on
all pistons, so obviously I needed to go buy a compression tester.
I went to Sears and bought a $25 tester and did the standard once-without-oil, once-with-oil test (oil improved compression on all pistons by
15psi)
Question though... One of the pistons was down by 15 psi from all the others (all were 195 except piston 3 was at 180) The oil test raised ALL
pistons by 15psi, so they were still off (210, 210, 195, 210).
Does this point to a valve problem, since the rings seem to have improved an identical amount when given oil?
I'm going to clearance the rockers and examine the valves anyway, so I may just answer my own question but... Anybody have thoughts on this?
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britishtrident
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| posted on 11/11/05 at 09:20 PM |
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Very slight variation probably one valve not seating quite as well as the others all in all very good compression for a high mileage engine --
best left untouched just check the valve clearnces.
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mark chandler
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| posted on 11/11/05 at 10:34 PM |
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Could indicate worn cam lobes, sometimes you can see the compression going up on some cylinders !
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smart51
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| posted on 12/11/05 at 04:08 PM |
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I've done a compression test and the results are not too good.
1 - 110 psi
2 - 98 psi
3 - 129 psi
4 - 103 psi
each of these readings goes up by 1 psi after a few drops of oil have been dripped in through the spark plug hole.
Mr. Haynes suggests that the minimum pressure should be 192 psi with 206 psi nominal and 213 max, and with no more than 14.5 between max and min.
my lowest cylinder is half of the nominal and there is 26 psi max difference.
I did the test with the engine warm rather than really hot. Would this make much difference?
What could be wrong other than valve seating and head gasket? How do I check and how do I fix it?
[Edited on 12-11-2005 by smart51]
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jack trolley
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| posted on 12/11/05 at 05:32 PM |
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Did you have the throttle wide open?
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smart51
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| posted on 12/11/05 at 07:59 PM |
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Oops! I realised, just as I was leaving the house earlier, that I hadn't opened the throttle during the test. Something for me to try
tomorrow.
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caber
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| posted on 12/11/05 at 08:50 PM |
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This thread looks interesting, I haven't tried it but this technique looks more helpful than a straight compression test:
http://www.locostbuilders.co.uk/viewthread.php?tid=34279
Caber
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smart51
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| posted on 13/11/05 at 10:19 AM |
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Repeated the compression test this morning with the throttle wide open and all the spark plugs removed. These are the results in psi without / with
oil
1) 155 - 155
2) 95 - 99
3) 151 - 156
4) 153 - 155
the manual states 192 psi min, 206 nominal and 213 max. 155 is 75% or nominal, 95 is just rubish.
What can the problem be?
[Edited on 13-11-2005 by smart51]
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mnr laptop
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| posted on 13/11/05 at 10:22 AM |
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try a little oil in the low cylinder to see if the rings are knackered,( this should seal some of the affected area and will give an increased figure
) as by the sounds of it there is a problem with either piston rings or valve seats / valves
hope this helps
marc
another thought
are all the butterflys openening ok
[Edited on 13/11/05 by mnr laptop]
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Triton
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| posted on 13/11/05 at 10:38 AM |
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Valve seats burnt perhaps as R1's get proper caned and why not if the motor begs to be thrashed
Is there any info anywhere on whether the valves shrink into the head like the 400cc screamers do?
My Daughter has taken over production of the damn fine Triton race seats and her contact email is emmatrs@live.co.uk.
www.tritonraceseats.com
www.hairyhedgehog.com
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smart51
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| posted on 13/11/05 at 01:18 PM |
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I tried it with a bit of oil. That's what gives the two figures for each cylinder. The difference with oil isn't very big so the problem
is likely to be in the head, isn't it?
The butterflies are all opening nicely.
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