My bus is possessed!

[Geoff]

The radiator cap is only 4 psi on a Detroit Diesel.

[Iceni John]

The radiator cap is only 4 psi on a Detroit Diesel.

OK, thanks for that.   I thought that some caps were as high as 12 PSI.   My cap has a 7 stamped on it, so I assumed that was its PSI.

Thanks, John

[Geoff]

If it says 7 it is the wrong cap.

[Dave5Cs]

Check your oil is there any coolant in it?

[Iceni John]

Check your oil is there any coolant in it?

Oil level is still exactly the same as before, no change there.   Tomorrow I'll drain a little out to check it, just to be sure.

More rain is forecast for next week, maybe, so that will be my next chance to get to the bottom of this mystery.

John

[Geoff]

Unless you seal the hose going into the collection jug you're not going to eliminate the most likely cause of the problem.

Oil level is still exactly the same as before, no change there.   Tomorrow I'll drain a little out to check it, just to be sure.

More rain is forecast for next week, maybe, so that will be my next chance to get to the bottom of this mystery.

John

[Iceni John]

What's strange is that this has never happened before, even during heavy rains here.   I've had the same surge tank and overflow bottle for a while now  - nothing's different there.   It's started happening only after I've completely redone the entire cooling system last year, so that's why I'm thinking it may be related to my recent work, but what and why I have no clue.

I checked my radiator cap yesterday  -  it is a 4 PSI cap, so I'm OK.   I originally thought it was 7 PSI because the number was so indistinct.   Good, cross one thing off the list.   Next weekend I'll pressurize the cooling system to 5 PSI and see if anything weird happens.   I also checked my oil yesterday  -  it seems OK, no obvious coolant in it, and the engine still bars over easily with a 40" breaker bar (at least, as easily as it ever does).

If after this week's forecast rains I'm still no closer to solving this mystery, then I'll just silicone everything potentially leakable and hope for the best.   By next weekend I should also have heard from the makers of my exploded hydraulic fan motor whether they will be nice enough to warranty it or not.   If they do, great, and if they don't I've now come up with a workable Plan B to use a regular-rotation hydraulic motor of any make or model that will drive the fan by a pair of V-belts.   This way I can use a readily-available standard motor to power my opposite-rotation fan without needing some overpriced custom-made motor.   I'll also install a separate pressure relief valve on the high-pressure line to the motor "just in case", and a pressure gauge to know exactly what's happening.   Always something to do, or in this case redo.

Isn't bus conversion fun?

John