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Proper compression readings

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jaybird

jaybird

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For a '75 MGB with 133xxx miles, no rebuild?
 
...and all within a few lb/in sq. of one-another would be desireable.
 
& do a dry & wet test when you do it.
 
Chuck did the test last night at the shop (guys night). I have the readings, but not the details.
 
And...............................................
 
Or..............
 
#1 - 150
#2 - 145
#3 - 130 (after he added a few drops of oil it read 165)
#4 - 135
 
That doesn't look abnormal for a high-mileage engine. My advise is to continue using it as normal until a rebuild becomes absolutely necessary. You can try some Seafoam, but I would only do that as a last resort. It could knock a lot of carbon loose and do more damage than good.

Just drive it! /ubbthreads/images/graemlins/smile.gif
 
....but you are about ready for a valve job...next project: pull the head!
 
I thought an increase in compression on the wet test vs the dry test was indicative of rings...if there is no change, one has a bad valve???
 
Ah - you're right, Rick...I had it backwards....sorry, I was thinking about an engine I just pulled a compression check on...

....sorry, Janel, its about time to renew Emma's engine...but, you've probably got a summer or 2 left...what's the oil pressure?
 
I'm fairly certain it's the rings. Oil pressure 2 years ago when we bought her was 65-70. The last few months or so, it's about 55#.

I'm driving her til she stops running, then I'll worry about it. I have a $20 running engine in the garage (minus starter that we pulled off for Binabox) We can dump that engine in when we have to work on Emma's, no down time!
 
Exactly what I'd do (though I'd stop driving her when oil pressure got to around 25 or 30 so I didn't damage anything so that it couldn't be repaired).
 
I was concerned about the 50# of pressure until Chuck told me to stop obsessing about it. Oil pressure hits 40 I'm parking her.
 
Could always start on the engine in the garage now or soon and have it ready to go in when the time comes. You know keep a spare ready to go. At least the short block.

I did that for years and never had a down day for an engine change. Would do it in the evening after work and drive it to work the next day.
 
[ QUOTE ]
Could always start on the engine in the garage now or soon and have it ready to go in when the time comes. You know keep a spare ready to go. At least the short block.

I did that for years and never had a down day for an engine change. Would do it in the evening after work and drive it to work the next day.

[/ QUOTE ]

Yeah but you've got an engine the size of your average Kitchen-Aid mixer... prolly didn't even use a lift did you?

/ubbthreads/images/graemlins/devilgrin.gif
 
Noop, no lift, a short peice of 2x4 and rope. Daughter on one end me on other. Striped down to short block it is not too bad a deal.
 
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