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914World.com _ 914World Garage _ Low Compression

Posted by: Bartlett 914 Sep 23 2005, 03:29 PM

Hi all

I recently picked up a 74 2.0. This car has not run in 20 years. I pulled the gas tank and fuel pump which was a mess. I changed the oil and I pulled the plugs. The compression is even on all 4 at 70 lbs. I know this is quite low. Is this to be expected? Should I try to get it started before doing another compression test or should I just resign myself that this motor must be rebuilt. I does have 88K on it.

Thanks
Mark

Posted by: MarkV Sep 23 2005, 03:35 PM

All 4 the same, that is good. Are you holding the throttle open when you do the test?

I would drive it, 88k isn't much.

Posted by: Bartlett 914 Sep 23 2005, 03:38 PM

Hi Mark

No I wasn't holding the throttle down. I will try that. The battery is also begining to get a little weak. I was never able to get the oil lamp off.

Mark

Posted by: Crazyhippy Sep 23 2005, 03:41 PM

depending on how long it's been sitting, it might need some miles to let the rings re-seat to put up a decent compression #...

Sounds like a combination of a weak battery and a closed throttle caused this one though.

Re-check w/ a fresh battery and the throttle WFO

BJH

Posted by: Bleyseng Sep 23 2005, 04:25 PM

wedge the TB open while you turn the motor over lots of rpms. A fresh battery helps.
Try a third test by squirting a tad of oil in each cylinder before testing and see if it goes up.

Posted by: SirAndy Sep 23 2005, 04:45 PM

QUOTE (Bartlett 914 @ Sep 23 2005, 02:29 PM)
This car has not run in 20 years.

just my humble opinion, but *ANY* motor that has been sitting for 20 years (or 10, or 5 for that matter) should be taken apart before you even try to turn it over.
unless it was stored *correctly* in a climate controlled enviroment where moisture in the air isn't a problem ...

god knows how the internals look like (think RUST) and you might just kill a bearing or two or add some nice grooves to the cylinders from simply turning it over ...
Andy

Posted by: jd74914 Sep 23 2005, 07:13 PM

QUOTE (SirAndy @ Sep 23 2005, 05:45 PM)

QUOTE (Bartlett 914 @ Sep 23 2005, 02:29 PM)
This car has not run in 20 years.

just my humble opinion, but *ANY* motor that has been sitting for 20 years (or 10, or 5 for that matter) should be taken apart before you even try to turn it over.
unless it was stored *correctly* in a climate controlled enviroment where moisture in the air isn't a problem ...

god knows how the internals look like (think RUST) and you might just kill a bearing or two or add some nice grooves to the cylinders from simply turning it over ...
Andy

I'd atleast spray some marvel mystery oil down the spark plug holes into the cylinders.

OT: Is your car the one in your avatar? Cause if it is its a 75 or 76

Posted by: Bartlett 914 Sep 24 2005, 10:51 AM

Thanks for the input.
I have read several posts about people starting and using motors that had been sitting. I wanted to see if it would run. I have decided to pull the motor. I see too much of a chance to ruin this motor.

The motor is in a project 74 car I picked up. My avitar is my regular car and is a 75. I plan to rebuild this 74 motor and install it in the 75.

Mark

Posted by: jd74914 Sep 24 2005, 11:12 AM

Ok, that makes sense now. You shouldn't need to rebuild the whole thing. Replacing the rings should give you better compression. (I personally would redo everything so you'll have a new and hopefully trouble free engine)