Thread: Did You know this 'Can' happen to a diesel (Death by oil)

Hi All

Thinking about this, but not having access to a 2.8, I wonder.

Being a bit of a goose myself a while back, I managed to over fill the engine on our ride on mower, the oil was fed into the carby by the crankcase breather, smoke and rough running was the result, with thankfully no long term damage.

The excess oil could have back up the oil return from the turbo, this would have strained the friendship of the turbo's seal.

But if the air ways from the turbo were clean of any oil, then I wouldn't look any more at the turbo, but instead, work out whether oil had built up in the rocker cover to the point that it was forced pass the valve stem seals.
.

As was stated early on, when I removed all the intake plumbing, pre and post turbo, there was signs of excess oil. Half a cup came from the turbo - intercooler bottom hose. Half a cup came from the intercooler itself. The main intake line had about a spoon full, including the bottom of the airfilter being oil stained/wet.

Yesterday I had some running around to do, and was able to pic up a compression tester gauge and hose. I also mangaged to pick up an old injector same as mine. The hose on the gauge has a quick connect air fitting and I was lucky to have the male fitting at home (USA type not so common here). I gutted the injector (which was a *****) and bored it out through its length, cut the threads off it and the fitting then welded them together. Cut the tip off, cleaned it all up and loctited a grub screw into the banjo bolt hole for spill return. Just waiting on the lcotite to cure and I will atempt to perform a compression test on each cylinder.

I had a look in the 300tdi manual and saw a figure of 348psi when warm. Now I havent found the compression ratio or psi figure for mine. So:

If my engine has the same comp ratio but a larger bore and stroke does that mean a higher psi reading?

what would I expect a good 300tdi to read when cold?

The added volume of your gutted injector will give a lower reading. It's probably best to check your tester on a known good engine and compare those engines.

But I suspect it's readings across the cylinders you are most interested in for variation. So absolute figures won't matter as much.

If you multiply CR*15 then you will get the absolute minimum value you should get - in this case ~292 psi. (19.5:1). That is the value you would get cold if you do not inject any fuel and the air does not heat up while being compressed.

So if you get less than that you will know something is wrong. I expect you should get around th 325 psi mark cold.

Make sure the batteries are fully charged, and remove all 4 injectors before testing.

why do I remove all 4 injectors before testing? In the RAVE it states to warm engine up (I cant), remove #1 injector and replace with dummy Injector/testor. Disconnect the IP solinode lead and crank for 10-20 secs....repeat for each individual cylinder.

Originally Posted by Dougal

The added volume of your gutted injector will give a lower reading. It's probably best to check your tester on a known good engine and compare those engines.

But I suspect it's readings across the cylinders you are most interested in for variation. So absolute figures won't matter as much.

The RAVE manual shows a full length dummy injector. I have NOT seen one in person so have NO idea of the internal bore. Mine is drilled out to 4.5mm in the main body.

At this stage Im just trying to get a base line and also see if there is a difference across the cylinders as you said. If its near ball park and all even, I will continue to try and start. If one is low or all lower than should be, I suspect it will be strip down time.

Originally Posted by uninformed

why do I remove all 4 injectors before testing? In the RAVE it states to warm engine up (I cant), remove #1 injector and replace with dummy Injector/testor. Disconnect the IP solinode lead and crank for 10-20 secs....repeat for each individual cylinder.

Mainly so the engine cranks faster, giving you a better reading.

the other reason you pull the plugs is so that in the event that something goes awry the engine wont try to start.

watching an idiot try to do a compression test on a 4bd1 sent the workshop gauge halfway across the room. aparently the correct way to do a compression test on a diesel is not.

remove glow plug #1
screw in compression tester
stand on the accelerator to open the butterfly
Key engine on starter
panic at the noise of the top half of the compression tester going elsewhere

Dont forget the absolute pressure in this case is not as important as the variation I work on 5% difference, you may also want to do it with the intercooler-intake hose removed.