Forums Forums Enthusiast Forums A - Z Autowirral Compression test results

Comp tested the 520 this morning,here are the results

Cyl 1 1.1 bar average and holds
Cyl 2 1.1 bar average and holds
Cyl 3 1.1 bar average and holds
Cyl 4 0.7 bar average and holds
Cyl 5 1.1 bar average and holds
Cyl 6 1.1 bar average and holds

Whats up with cylinder 4?? its not leaking but its down on pressure.

just to correct something. Its 11 bar,and 7 bar.not 1.1 and 0.7

it might be down to a valve not seating properly it doesnt mean it is a worn bre or ring.

thing is,after ive stopped cranking it it holds the 7 bar,im gonna try again tomorrow with the expansion cap off (to see if the air is being pressurised in the water system) if it still holds the 7 bar then ill get the water pump on and use optimax,red-ex and intake cleaner to see if its down to dirty valves and whathaveyou

Try them again and see if the readings are the same ?

A little tip for you Mr Scoopy.....

Do them a second time but put a cap full of oil in the spark plug holes first, then compression test them, if the compression comes up then the problem lies with the piston or rings (The oil seals the worn piston or rings to increase the compression), However if the readings are simillar then the problem must lie in the head (Valves or head gasket maybe).

Hope this helps.

Beat me to it

How did we get on Mr Scoop ??

we have'nt done it yet mr scooby.Ill do it next week probably,however,according to the E34 forum im on its rather common for the head to crack between an exhaust port and a water jacket on cylinder 4. Meaning im pretty much boned,im also being advised to change the water pump and run it,if it doesnt exhibit signs of head failure then im to just use it they say (implying that if its just valve seals or rings it'll be ok for thousands of miles) if however i do lose water (or oil,or both) then obv i need a new head (head gasket if im lucky) which....TBH....i cant be bothered doing i'll do the piston rig check next week, aswell as taking the cap off the expansion tank to see if it still holds 7bar (theoretically the pressure shudnt hold in the water system if the expansion cap is off right)