Quote:
Originally Posted by Laird Scooby
You almost certainly need a new expansion tank cap! 
Yes, they are prone to failure.
That level is too high!  Should be on the "MIN" mark or just above when cold, the big clue is in the name of "expansion tank" - it allows the coolant to expand and get to the "MAX" mark when hot. Over that and it will escape via the easiesst route which could well be the cap.
Try a new cap, get some new Jubilee clips and any others you find weeping, renew them. Given the B200 is known to be prone to piston slap on #4 cylinder if there are no other coolant losses after renwing the cap and the hoses/Jubilee clips, i'd accept it as the car getting older. As someone else mentioned, dropping some engine oil into the cylinder (via the spark plug hole) and repeating the test will confirm if the rings are worn.
Just to confirm, when you did the compression test, did you pull the fuel pump fuses and open the throttle wide for each test?  |
Thank you for the info,
if it's just my cap that is good news. I let the water level go so low it is just visible and still it comes out of the cap.
I didn't pull any fuses, no. I smelt the fuel during the test but didn't look for the correct procedure.
As my gauge didn't hold pressure it was difficult to see the exact pressures.
I wonder what the pressure was with a new engine because; as I mentioned, "the tank" seems under powered. My 145 I seem to recall was a lot more sprightly, the 940 is probably a heavier car, I've owned it since 2005 and it has always felt sluggish till it's up to 45mph plus.
Many thanks for help Ken.