Too high compression? Should I worry or be happy?

[Syncronorth]

This car (2.1 DJ westfalia automatic) has been sitting for around 5 years and according to the previous owner the engine blows white smoke and don't have power, but he is the kind of guy who thinks its okey to replace fuel lines with free plastic straws from McDonalds so the smoke can be from something else, like the rusty non branded oil filter. I haven't tried starting it, but was surprised when I did a compression test:



16 Bar is something like 230 PSI, what can be the reason for this high reading? Should I worry or be happy? 

[SyncroMatt]

Has the engine been rebuilt previously? It may have been built with too high a compression ratio. That could lead to the high compression figures you see. For example if the heads have been fly cut and the head chamber volume reduced

Too high a compression ratio could lead to knocking/pre detonation which can cause allsorts of
damage. Broken ring lands, holed pistons etc...

Ideally you need a leak down test as a compression test only gives you a measure of the momentary, max pressures being created but not how quickly that dissipates.

Be grateful he didn't tell you it runs great. At least he is being upfront about an issue.

IIRC 200psi is the upper limit for a stock DJ

More data required... Matt

P.S. an expert will hopefully come along soon...

[ajsimmo]

I'd be sticking a camera down the spark plug hole to see if they're DJ pistons.
One possibility is that someone stuck a 76mm crank in, then machined 3.5mm off the top off some DG pistons. A wild guess, but it would have a similar outcome to that described.
Or maybe they lapped the barrels into the heads a la air-cooled, then left out the fire rings?
It's a rum'n, any road.

Sent from my ONEPLUS A3003 using Tapatalk

[davidoft1]

Has it run yet ?

[Syncronorth]

Thanks for all your replays and suggestions

The seller is very honest, I even tried paying more for the car as I got it too cheap but he wouldn't expect. He don't know anything about the car history but he had it for around 10 years and used it for around 5 years before it was parked because he couldn't make it run. I did try to ask what he has done to it but seems like he don't remember, he have around 50 cars so that's understandable.

I have just finished changing some previously burned electrical wires, adjusting valves, new plugs, rotor, fuel, fuel lines, oil+++

Was just trying to set the timing manually but couldn't move the distributor. Will try again tomorrow and will hopefully be ready to fire the engine up.

Unfortunately I don't have a leak down tester or camera that's go inside the cylinder head but will look at buying it.

Let's see if it starts tomorrow.

[Aidan]

have you tried that tester on another engine ? it may not be accurate, just a thought

[Syncronorth]

I have used it before, but will test in on another running engine today.

I can only slowly turn the distributor, but it seems to be stuck in the engine case. Is that normal for a engine that's been sitting? Shuld be only the seal or rust holding it down?

[Syncronorth]

Did a cylinder test on a running 2.1 DJ
1#12
2#11 
3#11
4#12.5 
Guess its possible that the tester shows too much, will try to borrow one just to make sure/

I did start the westfalia and it runs and sounds just like I would say any old WBX set on manual timing and some small exhaust leak does. Drove it 20 meters (don’t want to run it to long before I have changed the gear oil). Was some white smoke the first 2-3 minutes and some oil dripping from the exhaust, guess that can be described as normal on a short run?   

 
Just as a note Temp1 sensor is defective, Temp2 Sensor is blocked and wires cut, alternator is not charging, air filter is missing.
Discovered that one screw hole is missing from the digijet bracket so guess this engine setup was not how it left Germany in 1985.




 

[Aidan]

if it's had water sat on the engine or a coolant leak then water can get in and you get corrosion above the o ring on the stem of the disi, it's not uncommon, you are better off with a slightly weepy o ring seal 
oil in exhaust I'd be checking oil level and valve settings
was it always a 2.1, was it always a DJ ?, missing screw could be original, I think I have seen a DJ with only one lower ECU plate screw before, it' can be nicely wedged in there so doesn't vibrate if top hole is done right