Compression test readings 110, 135, 125, 135 opinions?

[tristanblue]

Picked up a `71 bus recently. Driven here from California around 2006 and parked. The bus had the trans replaced with a 6 rib and a dp 1600 with new case, pistons and rebuilt DP heads done some years ago by previous owner. Since the bus has been driven and there is miles on it, but I am unaware of the exact mileage and the drive trai is quite dirty. The bus ran and drove when we picked it up recently but gas tank was rusty and carb plugged up so it was only driven a little down the road and back but seemed to run strong.

We pulled the engine and trans to do some servicing, main seals, axle boots, stuff like that. Upon inspection of the engine it looks to be healthy. The#1 main bearing is tight in the case, no end play is dead on and no slop or movement of that bearing in the case at all. All the main bearing studs, head and case sealing nuts were all dead on for correct torque. We decided to do a compression test. Here is specs.

-Fresh charged 12V battery
-engine on ground
-engine was cold and been setting long time, NOT warmed up
-spark plugs removed

#1 110
#2 135
#3 125
#4 135

Re tested again and exact same results. Then squirted a couple shots of oil into all 4 cylinders and re tested

#1 150
#2 160
#3 140
#4 150

So couple of points here obvious we see #1 is low at 110 dry. Difference between the lowest and highest is 19%. I know lot of folks say within 20% which this is on the fence for that. But the engine was cold as well, wondering if that would make much a difference. The shot of oil in the cyl really brought that #1 up so assuming there the wear is in the rings. So from what all I have read these compression readings are boarder line. So looking for opinions on what to do. Here is what we want to do with the bus.

It is original paint, patina bus. We just want to make a driver out of it. Take the family to the lake on weekend about 1 hour away. Will not be making long hauls that type stuff. We would REALLY like to drive it this summer. I fear pulling the heads is going to turn into a full rebuild and at the moment I have like 3 other project vws in various states of tear down.

What ya think, clean it up and run it or do tear down. I could always just drive it for summer and do the engine over next winter.

T

[evanfrucht]

That will work fine as is for the summer, you could easily just enjoy it. Realiabilty should be no issue at this point.

On the other hand if you have enough time on your hands and are very motivated you could probably do the work fairly quick if planned out well.

You would need new heads, get a set of new pistons and cylinders, new pushrod tubes, verify deck height, chamber volume, get CR where it's supposed be, etc. Make sure to clean everything well before assembly and free of grease or dirt, get the cylinders and PR tube seals sealed up nice, etc.

Not a huge job, it will give the engine a little more pep if done right. But then again, as you say, that could be saved for a full rebuild when the time comes.
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1967 Bug ( the daily rod )
1964 Fury Wagon ( the pavement shredder )

[bsairhead]

Run motor till hot. change oil, let it cool down overnight adjust valves. Run it hard, let cool down but not cold. Pull all plugs and coil wire do compression check with throttle fully open. Could be a sticky ring or valve issue or head sealing problem. My guess is a ring issue because of your wet numbers.

[oprn]

It's a good running USED engine. Take the purse off your shoulder and DRIVE it!

Sorry that's a bit harsh but man! It doesn't have to be new and after you make it new and drive it a bit it will be used again! That engine will last you 3 or 4 more seasons as an occasional summer driver. Maybe more! I consider anything above 80psi to be a driver. Watch the oil level, watch for exhaust valves tightening up, and drive it with respect.

Go enjoy your Bus!
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[jpaull]

[nextgen]

Oprn and the rest you guy, I love this post, it shows what you know and from your experiences with air-cooled cars, when to sit back and enjoy it, knowing the inevitable will happen, just be prepared for it.

I am came to that point years, as you may have read, I had the bubble paint problem due to the foam in side walls of my bug. Read my resent post ' Vent Plug'

One foam is easy to remove not mine after 74 the stuff is like a rock, I tried. Well came to the conclusion, If I can't remove it, I will live with it and try to prevent more water to entering. Time will come when I will have to do something but that may take years, if I stop the moisture now. The $2000 repair job makes you think twice. Any thing can happen in a few years.

Just like what it is going to cost tristanblue when the time comes.
Enjoy the bus.
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[oprn]

I mean really! Guys spend huge dollars building the PERFECT engine with all the BEST parts and tricks, then stuff it into a rusted out piece of crap, call it patina and think they are hip!

What is wrong with a good patina ENGINE? Ya, it's not perfect but it runs good and gets me where I want to go. If patina is good enough for the body and everybody can see the body then why can't we run Patina engines? If anyone doesn't like your patina engine then shut the deck lid... and drive away.

I vote we start a patina engine movement. Qualification? Just has to run good... OK? We are hip too!

No offence intended to the OP and sorry to hijack the thread. My advice to you is kick OCD in the solar plexus and run it with pride! Your engine is a survivor!
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We had the stone age, the bronze age, the industrial age and now we are in the age of mass deception and mind control for corporate profit. (The mass media age)

[clonebug]

I've run an engine with 160 lbs. compression.....120 lbs. compression..... 90 lbs. compression..... and even one with almost zero compression due to valves leaking from POS heads...
One thing in common........They all ran.

Drive it.........
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[Dan the workingstiff]

I have a secondary riding lawn mower. It has bern burning oil for years. This early spring it would die at an extended idle period. No it idles fine. It still burns oil, but doesn't load up. Put it in and run it.
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'69 Beetle
'66 FG buggy
My other air-cooled's
'76 IH 1200
'75 IH 1200

[FreeBug]

Those cold engine readings mean nothing. At running temp, with no squirt of oil, and you'll have useful data.

That difference in pressures show roughly a 2 bar difference, which is the facttory limit before a rebuild. Make sure it's not a leaking exhaust valve, and if not (it's not probable anyways), run it; it will probably run fine for years. The crappier the engine, the better they run, somehow. If it had new heads, new carb, new distributor, new P/C, line bore, etc..., you'd be here asking about how to get it running ok.

[oprn]

[Shane Tuttle]

I'm in agreement with oprn. Just drive it.

If you really want to have a better idea of what's going on, ditch the compression check method. Perform a cylinder leakdown check, instead. It's more telling of what is happening to your top end and can further dial in the source.

Otherwise, drive that bus.

[GARRICK.CLARK]

Do a cold engine valve adjustment and do another comp check.

[nextgen]

My wife drove a Sqbk back in the 70's and it was loud, thought it needed a new muffler. She drove it like that for a year, winter cold and summer heat. Starter and ran, never complained about how it ran, only about no heat and exhaust fumes

When the summer came and I was able check it out, I found the head on 1 and 2 side loose and #3 valve burned.

So it was not the muffler it was the lose head. Talk about no compression!!

Could not do that with a water cooled car...
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