compresion issue in a 1.8, low on no. 4 Options

[broomhandle]

I have a 1.8, and it runs like a bus motor, its a EC 1.8. i can be driving and it will be a 914 for a few seconds and then back to a bus...

so, i did a compression test

4= 80-60
3= 100
2= 120
1 = 100


and my plug on no. 4 is black.

new plugs.

what could be going on?

the valves are not adjusted. and also, i feel like its timed right. but, then you drive it.... and it just not timed right...

what could be going on with No. 4? and why would No.2 be higher? because its the opposite side? compensate?

im a lone 914'er... and Vdubber... you guys are the only people to ask! (IMG:style_emoticons/default/smile.gif)

[aircooledtechguy]

It sounds like you have 2 un-related issues going on.

You NEED to do a proper valve adjust on the motor BEFORE doing a compression test. The motor also needs to be warm in order to get accurate readings. Pull all plugs and hold the throttle wide open while you crank it. Low readings can be from leakage at the valve or past the rings. If you have oily goo on the plug and a valve adjust doesn't make things better, I would suspect the rings.

The black plug could be from a few other things too:
1. bad injector; sticking open?? Easy to check. Pull the injectors and run the fuel pump to see if it leaks.
2. intake/exhaust valve seat coming loose. This will cause it to run poorly (intermittently) and explain the low comp. # on #4. Dangerous situation since when it fails, it junks the whole motor. You will discover this while doing that valve adjustment you need.
3. Vacuum leaks. Use a can of carb cleaner and spray around ALL joints/seals in the intake system. If the RPMs raise, you have found a leak. Do not stop looking if you find a leak, as there may be more than one.

[timothy_nd28]

The bad plug, is most likely a failing non firing fuel injector. It explains what he said earlier about the car driving like a porsche sometimes and other times like a bus.
You must adjust your valves, and warm the engine up before doing any compression tests.

[broomhandle]

it has a 32/36 weber.

[timothy_nd28]

Damn, anyways, I had a bad injector a month ago, and that's how my plug looked. Start with the compression check

[broomhandle]

ill start with a valve adjust. any easy way of going about?

just drop the engine a bit, and loosen up the trans mounts?


i wish i had a lift.... (IMG:style_emoticons/default/smile.gif)

[LotusJoe]

ill start with a valve adjust. any easy way of going about?

just drop the engine a bit, and loosen up the trans mounts?


i wish i had a lift.... (IMG:style_emoticons/default/smile.gif)

Loosening up the motor mounts isn't going to get you much room. There should be enough room. You may have to remove the heater piping going into the exchanges, but that's about it. It's cramped but there is enough room.

[brant]

it could be that your motor is just shot...

but that is the bad news
its worth doing a valve adjustment and maybe leak down to know

buy a haynes manual and its relatively easy with a jack and jack stands.....

or go to pelican and print a how to article at a minimum.

[broomhandle]

it could be that your motor is just shot...

but that is the bad news
its worth doing a valve adjustment and maybe leak down to know

buy a haynes manual and its relatively easy with a jack and jack stands.....

or go to pelican and print a how to article at a minimum.

yep agreed.

im going to do the valves, new gaskets and check the head bolts.

after that.... if its a no go. im done with the motor, a rebuild maybe or just done! (IMG:style_emoticons/default/smile.gif)

[brant]

unfortunately you can't do the head bolts without dropping the motor and stripping the tin.

but they would be fine anyways.
so let us know what you find out from the valve adjustment, retest.