1990 320i compression problem (i think)

Post Fri Feb 17, 2012 8:31 pm

Hi Guys , My car has been sitting unused for 3 days, went to start it today and it would not fire up , after full gas and maybe 5 turns of 30 second bursts it reluctantly fired up , while idling i thought the injectors sounded a little loud , to clarify i removed the oil cap and found there was no compression , i turned off the engine and turned it again and it fired up first go , to be honest guys i really do not know what to do next , any checks i can do ,possible reasons , would really appreciate some help as i do not want to drive it if i could cause futher damage ,

Post Fri Feb 17, 2012 9:02 pm

teatime39 wrote:to clarify i removed the oil cap and found there was no compression

Clear as mud

You mean you got oil spitting out, possibly caused by Blow-By?

That's not a guaranteed test of lack of compression, and certainly isn't enough to go on when diagnosing a sick engine (although it does help). Get a proper compressor tester on it first to make sure.

If you want more specific help as to why it was hard to start, you'll have to tell us what car this is first.

Post Fri Feb 17, 2012 9:08 pm

its a 1990 320i cabby , no spitting of oil when cap is off , no blowing at all , thinking about it my heat guards are totally gone as in almost hanging off , do you think if the gaskets are gone on the manifold it would cause the loss of compression ?

Post Sat Feb 18, 2012 9:36 am

started first time this morning , used wd40 to check for air leaks ,all seems ok , the bottom of my exhaust manifold has a stud broken off as there is no bolt and the stud is level with the manifold and i see fumes so i think the whole lot has to come out for me to be able to get to it, C191 plug which i believe is under the inlet manifold is ok ,no green or rust spots so it would seem the problem with starting is it lies unused for a while . i took the oil cap of again while idling and it does effect its idle a little but still no real compression .

Post Sat Feb 18, 2012 9:45 am

teatime39 wrote: but still no real compression .

I'm still confused. What do you mean by "no compression"? If there was no compression, the pistons wouldn't be going up and down.

Post Sat Feb 18, 2012 9:59 am

in the past when i would take the oil cap off while the car was running i could feel lots of air coming through and it would run lumpy . now it has little effect on how the engine runs and no blowing at all