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Mon Aug 11, 2003 5:19 pm

I was doing a regular tune-up on my bug last weekend and decided to change the spark plugs - and since they were out I did a compression test.
The pressure in all four cylinders was around 90psi :cry:

I bought the 74 conv three years back - but didn't drive it much and always stored it for the winter. This is the first time I checked the engine compression and was surprised that it was so low. I guess it is due for an engine overhaul now.

My question is - how long can I safely drive this engine before doing the overhaul? Ideally I would like to drive it till the end of this summer and then do the rebuild. Or should I not postpone it and do it right away? How much more damage can happen if I kept driving it like this?

Any advice/comments will be much appreciated.
Cheers,
Casper

Mon Aug 11, 2003 6:29 pm

You'd be surprised. If it's not smoking and feels peppy enough, I'd wouldn't even worry about it until you start noticing the motor getting tired, or endplay, a puffs of smoke during startup.

If everything else is up to snuff in tour motor and you keep up on valve adjustments, oil changes, I think another 10,000 miles wouldn't be totally unheard of.

Drive it!

Mon Aug 11, 2003 6:40 pm

I agree with what Bob states in his post...but...

Just out of curiosity, did yo udo the compression test warm with the throttle open?

and did you do it AFTER a valve adjustment?or no????

and was it a screw in compression tester/hose? or a rubber ducky you just hold in the plug hole?

Mon Aug 11, 2003 7:06 pm

Another 10K miles!! That's wonderful to know :D
Now I can enjoy the rest of the summer in my sun big without worries (well... not too many anyway). Thanks UncleBob for that reassuring peice of information.

Keifernet, I did the test cold - after an oil change, valve adjustment and distributor tune up. It was a screw in compression tester - tightened it as much as possible into the spark plug hole with my hands (I have small hands), didn't use a wrench.

Should do it warm?

Right now I have pulled off the carb for a rebuild as it has been giving me several headaches recently. And the past few days it started leaking gas like crazy.... got a rebuild kit on order and will put the crab back on as soon as I get it.

Mon Aug 11, 2003 7:38 pm

Quote:
Keifernet, I did the test cold - after an oil change, valve adjustment and distributor tune up. It was a screw in compression tester - tightened it as much as possible into the spark plug hole with my hands (I have small hands), didn't use a wrench.

Should do it warm?
.

Yes you should do it warm, take it out for a couple minute drive and then pull the plugs and check it. 90 on a cold engine probably isn't too bad.

[/quote]

Mon Aug 11, 2003 7:58 pm

As stated above, do it with the engine at operating temperature, with the throttle held wide open. 90 psi is not that terrible. It's more important that the compression numbers be even. I think the old girl has some miles left in her yet.

Tue Aug 12, 2003 8:12 am

Yeah, 90 cold could become 100 when tested warmed up so it looks like your in good shape...

BTW, I have recently began testing in the aircoold.... the product called "RESTORE".... I have used it in a few of my personal water cooled rides namely a Toyota Camry with 200K and a Dodge PU with 318 v8 and near 300k miles and have seen ACTUAL results! the shit appears to work...

Tue Aug 12, 2003 9:11 am

Keifernet,

Have you posted your findings somewhere? If not, can you post them here? I'm leery of any of that 'liquid rebuild' stuff, but have a Bronco approaching 160K miles and she's getting pretty tired...

Tue Aug 12, 2003 3:05 pm

I have not posted any "findings" and I am not really going out on a limb for a testimonial at this time, at least not for air cooled as I just started using it in a few VW's.
As far as the stuff working well, the Toyota used to smoke a bit ( you could see it in the rearview at night when accelerating hard) and it was feeling kinda slugggish... 2 treaatments later no smoke visable and power was up significantly and milage. 28-29 mpg on freeeway at 70-80 mph! with the A/C on.. ( 2.0 L engine 1985 model, started test at 195,000 and now has 206K)

I have tried a few of the "other" additives, this is the only one I have seen do much of anything it said it would... IMO.... it does work .... so far so good.

Dodge Truck is running smoother too, still on the second treatment.

the stuff is not a "one time " miracle additive, I think it takes 3,000 for it to begin to work. I will be adding it at every oil change on my high milage motors.... Wal-mart has it the cheapest...