Engine compression and rebuilds

nutzforporsche · 02-02-2003, 01:55 PM

Hey all I have a question that is better suited for the pros.

Some background:

I recently purchased a 75' with a supposed rebuilt 2.0. Heres the story, it may be a long one, so bear with me. The PO told me that he got the car from a VW mechanic who owns a shop up the street. The mechanic said that the real owner came in and paid the full price to have the engine overhauled. The overhaul was performed, but the original owner never came back to get the car. After numerous failed attempts to contact the owner, he applied for title. He then sold the car to the guy I got it from. This guy told me that he probably only put 400 miles on the car, just driving it up and down the street, for the last two years. It has terminal rust on the longs, so he was afraid to drive it much further.

Ok finally to the real important portion of the story. The engine runs good except for the vac hoses needing to be replaced. OK no biggie... I warmed up the engine and decided to test this so called engine rebuild. I pulled out sparky three and only got 100. From this I was too bummed and decided not to pull the other cylinders.

I now know after searching the BBS here, that I performed the compression test incorrectly. I opened the throttle up with the coil wire off and still got only 100. with no visible leakdown. I didn't however pull the other spark plugs out during the test.

OK finally the questions after I have bored you out of your minds.

Would it make that much of a difference, without taking out the other sparkplugs?

Would a valve adjust help?

Even if the engine only sat for two years "inside and covered" after the refresh, would it show this low of a compression?

Is it low because the engine isn't broken in?
"Dumb question I know, but I have to ask."

Have I been lied to ?
Go ahead and marinate me in sauce and set me in the flame, its ok. Might teach me a lesson. Then I can go and teach this guy a painful lesson, in what happens when you lie and get caught in it.

Thanks All!

Steve

hardflex · 02-02-2003, 03:15 PM

not a pro here, but I wouldn't jump to any conclusions off 1 reading. It could be something simple like a faulty gauge. Once you have all the info, then you can draw conclusions.

I'd look for near even compression from all cyl's, regardless of what the gauge might say. I have gauges where the pointer came loose, so I just stuck it back on. But I still use it in a pinch. (I told you I'm not a pro)

How does the engine run? while spinning the engine does it turn evenly?

tryan · 02-02-2003, 03:39 PM

hot, fresh, new, fully charged battery. warm/hot engine

all plugs out, throttle wide open, pull the fuel pump relay and coil wire.

insert you comression tester and try again. be consistent on the number of times the engine turnes over.

is she still smokin'?

(a '72 boat i had had less that 85 psi and would still get to 95 % of top speed. sure was easy to start.)

Jim Smolka · 02-02-2003, 05:03 PM

Yes, a valve adj could held. Could also be some junk on the valves after sitting for a while.

Drive the car around for a while. Then see what happens.

nutzforporsche · 02-03-2003, 04:31 AM

The engine turns over quick and runs like a champ, with some high idle, due to the vac hoses. There is no smoke coming from the tail pipe. I put my CO analyzer on it and it was a just tad off from optimal. I'll go back and perform the compression test correctly this coming weekend. I hope like hell that its good to go.

Thanks for the insight!!!!

Steve

tryan · 02-03-2003, 04:41 AM

don't do a compression test, just drive it

nutzforporsche · 02-03-2003, 05:26 AM

Will do. Just hope it doesn't bust in half from all the rust underneath LOL

Steve

nutzforporsche · 02-03-2003, 05:33 AM

Tryan,
A bunch off topic. I notice you have a love of boats. Me too....I have a completely restored 71' SlickCraft with a straight six. Tried to sell/trade her to get a used six motor for my car, but no bites. Aw well I'll have to convince the G-kids to go out this summer.

Steve

tryan · 02-03-2003, 05:56 AM

i tow one to the correct craft reunion at six flags/ seaworld in aurora every june.

the jugs and rings probably rusted up while the car sat for two years. the compression might get better, might get worse. warm it up and stomp it.

i put straight 30w in the 914 for the winter and she was smokin' yesterday on the overun. hoping some 20w-50 will cure it.

nutzforporsche · 02-03-2003, 06:34 AM

Thats probably what I'll do. I'll change the oil, warm the sucker up and thrash on it some around the neighborhood. It could go either way on getting better or worst. The good thing I'll be close to home if it goes south LOL.

Steve

Mark Henry · 02-03-2003, 06:49 AM

Quote:

Originally posted by tryan
the jugs and rings probably rusted up while the car sat for two years. the compression might get better, might get worse. warm it up and stomp it.

Yep, drive it for a while and then do the test correctly.

tryan · 02-03-2003, 07:30 AM

you might squirt a little atf in each cylinder or some fogging oil and flip her over a few times with the plugs out. you might have a stuck ring.

nutzforporsche · 04-01-2003, 05:06 AM

Ok,
The snow is gone, back to the task.
I decided to really hammer on it around the area. Its peppy to say the least. I decided to pull the engine and tranny out last weekend. I got a new battery hooked up, readjusted the valves and pulled a stone cold / dry compression test. Here are the findings.

Cyl# 1 145

Cyl# 2 120

Cyl# 3 145

Cyl# 4 150

Please tell me that the #2 is not hosed?

Thanks
Steve

Bleyseng · Bleyseng's Garage

Try it hot as the valves still might have junk on them. Thats pretty good readings so I wouldn't worry too much.
Geoff

nutzforporsche · 04-01-2003, 06:52 AM

Geoff,
Would love to, however I pulled the engine to list on ebay. So warming her up would be a pain. I was just concerned on that cyl . Praying that it wasn't a sign of something wicked this way comes. LOL

jkeyzer · jkeyzer's Garage

I wouldn't panic over those numbers either... Could be better but you haven't done a valve adjustment or even driven the car much yet...

And yeah the engine should be warm, all plugs out, throttle wide open, and I disable both the ignition and fuel systems. No point making it more dangerous than it needs to be. Usually you need to crank for a few seconds to get the readings to stabilize. I usually test at least twice per cylinder.

nutzforporsche · 04-01-2003, 12:49 PM

Jeff,
I'd be doing great if I hadn't already pulled the darn engine! HA! So just maybe I'll be ok. If the #2 cyl is showing 120 cold then I would hope it would be even better warm. The other cyls showed good cold. I'll try not to sweat it....but its tough LOL

jkeyzer · jkeyzer's Garage

I see. Why'd you go and pull the engine anyway? Usually most things (valve adjustments and stuff) can be done without removing it. I have pulled an engine in a 914 before with some friends and it was not incredibly hard but more work than I'd like to do any given weekend.

nutzforporsche · 04-01-2003, 01:05 PM

Well,
This car was destined for ebay due to sniff.. sniff terminal rust.
Rest its little soul. I'm selling or trying to sell it on ebay, hoping someone can put it to good use. I need a new paint job on my car so I'm selling to get the cash together to do just that.

jkeyzer · jkeyzer's Garage

Aww, poor thing.

Another 914 leaves this place and goes into limbo.. err... ebay.