Runs like a dog - Compression test results

Thanks Snotty

Quick question, if only 2 pots were full of oil, why would the other two be similar?

When I tried to start it when 2 pots were full of oil, it would only have been the strength of the starter motor pushing the pistons, can it have done that much damage?

Compression test was done with engine cold, also, did not open throttle, how much difference would that make?

Would have any of the symptoms you decrirbe produce excessive smoke as it passed its MOT on that bit?

failed on a few others though.....

Thanks

Ed

 

certainly strange why all the pots have low readings and the same ,are you sure the compression tester is good?[test it on something else] ,btw does not realy matter if engine is hot/cold...

valves should`nt matter ,the tester measures the highest upstoke when both valves are closed ,all 8 valves cannot be acting up...If worried about valves take the rockers off and test...

 

Thanks

Think tester is good, borrowed of a grease monkey, one of those snap on bits of kit.....

It's got me a bit stumped, might try charging battery and trying it again.....

Someone told me (mate with van) that sfter new pistons / pots that valves should be reset after running a while, if so this hasn't been done.

Regards

Confused from Hellifield

 

You should maybe take things apart and have a look. Is it possible that you've mashed the crank? Not sure if it would be the same but I had a diesel which sucked up water, that snapped the crank in 2. Water and oil don't compress, so the even readings could be due to lower resistance now if you've got a bent or snapped crank.

 

From experience, you'd have got another 20psi or so if you'd opened the throttle. That's quite reasonable. I've driven buses that read about 40psi and they still go quite well. All readings being in the same ball park is good. I don't think you've damaged anything - I imagine the bus was the right way up for quite a while before you got around to starting it. If the barrels had been full of oil it simply wouldn't have gone round at all.

So - I reckon you should be looking at fuel/timing. But yes - do set the valves first as you would before timing carb adjustments even if it was all tickety boo.

 

I agree with Zed theres not enough power from the starter to damage anything by cranking it with oil in the pots it would just stall the motor, set you gaps and check the timing. How old is the fuel? that can go off quite quickly might be worth putting some fresh petrol in.

 

Check the obvious first..

Leads connected in the right order?
Take a plug out at a time and check it is sparking by earthing on the engine (not too close to the hole where fuel vapour is pumping out!)
Do the plugs smell of fuel when you remove them?
If its a twin carb is there fuel getting to both cylinder banks - can you see it spraying down the choke with the airbox off?

 

If you think that was dumb let me tell you the one about an empty tank that resulted in a new fuel pump....... ;D

 

if all the comps are even you'll probably find that it will be absolutely fine once up and running....i'd be tempted to boot it over for a while with the dizzy lead disconnected and then retorque the rocker bolts before attempting to set your valve clearances

 

Did you get oil in the carb?

Compression is low but equel so thats a good sign