1988 190 Oil Pressure Drops to 0 engine ratles

[Roy Duggan]

History:-

Car used daily untill 2-3 months and then left parked since,

Started up fine left running for 10-15 mins to throughly warm up, no apparent problem.

All looked OK drove 2 miles to nearest garage to check tyre pressures, never looked at the Oil pressure so could have been low.

From garage I took it for a short trip to check everything was working but after a couple of miles stoped at lights I noticed what sounded like a noisy tappet / top end rattle.

Drove off from lights after 4-500 mtrs later happened I took a look over the gauges...

Shock horror Oil pressure at bottom of gauge 0, quickly pulled over and turned off ignition.)

I let everything for about 20 Mins to cool down to below 40deg on the water temp gauge checked oil level - ok - midpoint on dipstick.

Tentively started up and watched oil press gauge - quickly sprung up to max Oil Pressure (3 on gauge). Engine nice and quiet.

After aprox 30 secs gauge started to fall, then over another 30secs going seatidily down to 0 - I cut engine at this point. topped oil with Castrol 20-50 High Milleage.

Waited another 10mins (I no longer have breakdown recovery so decided to see if I could limp home gently in 30 sec increments allowing the oil to cool down between spurts - guessing the loss of pressure was tempreture related.

I eventually made it home, I could accellerate to 40mph before the prssure dropped down from 3 on the gauge and I would select neutral and cut the engine as soon as it dropped below 2.

It took about 10 run/coast burns to get home.

I suspect it was not tempreture related as on the last few runs I found I could run the engine and after a only a few tens of seconds or coasting I could restart again and the oil pressure would jump straight back to max pressure for 20-30 sec again.

It is almost as if the oil is being pumped away from the sump faster than it can get back to the pickup point.

I was thinking an filter and oil change might be the best starting point.

Any ideas whats going on and all suggestions gratefully recieved.

Roy

 

[Ian B Walker]

Sounds very like your main bearings are just about shot. Sorry my friend but this could work out expensive. By all means try changing the oil and filter, it may just work, but I have my doubts.

 

[television]

I think it as Ian says by the sound of it, what is the mileage of the car

 

[newlaithe]

Could it be a flow restriction on the suction side of the oil pump,as in the course filter blocked or even the sump pan dented hence reducing the clearance between the sump and pick up point?
If so it may have enough flow for tick over and low revs,but higher revs could cause starvation..

 

[television]

I would think that even the chain tensioner could cause it if faulty, bur I think it is a sump off to find out what has happened

 

[wireman]

Isn't there an oil pressure relief valve on these engines? If so it could have gone wonky whilst standing. Bits of sludge or something bitty in added oil may jam the valve or its spring may be broken.

If it has gone bad there is a considerable chance that the engines main and big end bearings are past it because you drove it with no oil pressure, with luck this may be limited only to the bearing shells but if the damage is very bad the crankshaft will need to be reground.

I like Ian doubt that an oil change will mend it.

Newlaithe, The sump/oil pan is die cast on many mercs and any attempt to bend or dent it will crack it wide open, thats what happened to mine after I caught a speed cushion whilst braking.

The first port off call should be remove the sump and check those main and big end bearings you can with the engine in place and the oil pump and relief valve.