no compression on all cylinders!

[chet]

So I got this jetta from a guy. not running. He said it just died one day at a light. It still turns over fine. I decided to start with a compression check because if its down on comp I will rebuild it. I picked up a compression gauge from Princess auto and the one adapter is a direct match for the VW injectors!  

Anyways today when I did the comp check there was 0 comp. in all cylinders! Is this even possible? It has been sitting for around 4 months?

Is my new gauge screwed? What gives?

[Northboundtrain]

Do you know what happened when it "died".  Is there still a timing belt?

[935racer]

The tool for the job now is a leakdown tester. It will tell you exactly where the air is going.

[chet]

thanks guys! It still has the timing belt on it and its not a new one so it doesn't look like someone changed it.

I will try and get ahold of a leak down tester. I guess one for a gasser would work if I can get the right adapter to the injector hole?

[935racer]

Yeah a gasser one will work fine if you get an adapter for the injector hole.

[dieseldan]

If the engine is cranking faster than normal, this is a sign of very low compression.  The absence of suction at the intake will also indicate this.
Daniel

[chrissev]

So I got this jetta from a guy. not running. He said it just died one day at a light. It still turns over fine. I decided to start with a compression check because if its down on comp I will rebuild it. I picked up a compression gauge from Princess auto and the one adapter is a direct match for the VW injectors!  

Anyways today when I did the comp check there was 0 comp. in all cylinders! Is this even possible? It has been sitting for around 4 months?

Is my new gauge screwed? What gives?

sounds like the head gasket blew.  Cylinders are probably full of coolant.  Good luck with that engine, you'll need it.

[dieselweasel]

Yeah, with a blown head gasket you'd still have some compression, and there would be other symptoms.  

Don't go looking for a leakdown tester, check for compression with your finger at the glow plug or injector hole.  If you feel compression, then you know your gauge is NFG.  If there is no compression, you can pressurize the cylinder with air using a rubber-tipped air blower and listen for air in the intake/exhaust and crankcase.

[steve]

or it overheated and melted a hole in the pistons... although in my vast experience (1 engine) it melted the hottest piston first... and the rest survived.  Just an idea...

You could try just pulling an injector (or all of them) and blowing compressed air in it.  seal arround it with a rag or whatever.  Not perfect but it might give you some ideas.

[chet]

thanks I am going to try holding my thumb over the injector hole tonight. (kinda hard by myself!  :lol:  )

I can also take the valve core out of the pressure gauge adapter and use that to pressurize the cylinders. I was f$%cking with the gauge last night and I'm pretty sure its the valve core in the adapter. if I take the air nozzle and put it up against it I get nothing. If I take the adapter off and use the air on the hose itself I get 100 psi on the gauge (what my take puts out) Stupid cheap PA crap!  :evil:

[chrissev]

What scenario of blown headgasket would cause 0 compression in all four cylinders?  

Andrew

Usually happens when you warp the head.  I had it happen on a 1.7 gas engine rabbit, same scenario, engine just died at a traffic light after some high speed highway driving.  Took the head off, found all four cylinders full of coolant, head measured for warpage and found to be bowed in the middle.  Scrapped the engine and put in a 1.6 from a wrecked scirrocco.  It happens.

[dieselweasel]

What scenario of blown headgasket would cause 0 compression in all four cylinders?  

Andrew

Usually happens when you warp the head.  I had it happen on a 1.7 gas engine rabbit, same scenario, engine just died at a traffic light after some high speed highway driving.  Took the head off, found all four cylinders full of coolant, head measured for warpage and found to be bowed in the middle.  Scrapped the engine and put in a 1.6 from a wrecked scirrocco.  It happens.

I find it highly unlikely that a blown head gasket would cause 0 compression, especially if there was coolant in the cylinders.   It would have to be blown to smithereens and then some.

[chrissev]

What scenario of blown headgasket would cause 0 compression in all four cylinders?  

Andrew

Usually happens when you warp the head.  I had it happen on a 1.7 gas engine rabbit, same scenario, engine just died at a traffic light after some high speed highway driving.  Took the head off, found all four cylinders full of coolant, head measured for warpage and found to be bowed in the middle.  Scrapped the engine and put in a 1.6 from a wrecked scirrocco.  It happens.

I find it highly unlikely that a blown head gasket would cause 0 compression, especially if there was coolant in the cylinders.   It would have to be blown to smithereens and then some.

No it wasn't really.  Once the metal rings around the cylinders stopped sealing, the fibre gasket couldn't hold the compression so I lost it on all four cylinders.  Then my theory is that once there was no more compression the coolant came in.  Ie, once the compression was blowing out the sides of the gasket, there was nothing to stop the coolant from flowing into the cylinders (because it was under pressure).  That was my theory anyway.  None of the cylinders had any compression at all when I tested them and like I said, they were full of coolant.

[Master ACiD]

if you took the head gasket off and just had a bare cylinder head on a block you would still get some compression. i know because i did that once on accident. it didnt run but i got abvout 45 psi on all cylinders.

its very hard to get absolutly zero compression. you would need a badly bent valve or a hole in a piston or something.

[chrissev]

if you took the head gasket off and just had a bare cylinder head on a block you would still get some compression. i know because i did that once on accident. it didnt run but i got abvout 45 psi on all cylinders.

its very hard to get absolutly zero compression. you would need a badly bent valve or a hole in a piston or something.

true.  would depend how long you waited though.  You'd get an initial 45psi but if you waited any time at all it would go down to zero.  If he's cranking it over, then looking at the gauge and the gauge goes down to zero very quickly then stays there, he'd think he had no compression but he would actually have a small amount for a small period of time till the air leaked out.