Hi. I had the question about the spark plug tubes and appreciate all the prompt responses I got.

However I have a problem with the same forklift, a 1998 Toyota with the 4Y engine running on propane. The engine oil became really foamy and beige in colour. I drained the oil, poured a few litres of old oil that I had into the oil filler on the valve cover and let it drain out through the drain plug. I refilled with 15w40 Shell Rotella and changed the oil filter. This was a week ago and the engine has been run since for maybe two hours. Oil Analysis at a lab showed water but no glycol in the oil. Also, last year I drained out green coolant and refilled with Detroit Diesel PowerCool Plus coolant which is red in colour. There is no trace of red colour in the oil, just beige. The coolant is a non 2-eha OAT and is silicate and phosphate free. I know Toyota likes a stiff dose of phosphates in their coolants.

I checked the oil today and the foam is beginning to come back. The oil was fine after the oil change and the engine running for ten minutes.

Coolant level has not dropped at all. I cannot tell if the oil level has risen.

The forklift operator pointed out that the engine is low on power and that all this coincided with him getting the propane tank refilled about three weeks ago.

The only sources of water I can think of is coolant, condensation and propane contaminated with water. I would expect water as a contaminant in propane to vaporise and exit through the exhaust rather than going in large quantities into the crankcase.

I am stumped. I am going to change the oil again and run the forklift on a barbeque tank to eliminate propane contamination, unless someone has other suggestions.