MT-FUEL-CORP

I have a 686st .. 1986...E237. It's not the original engine..I bought it as is...I had a ticking noise that would come and go..Thought it was a lifter. Turned out to be a bad head gasket...the ticking sound was coming from where the head meets the block in one spot. Once I figured it out, you could actually see it leak and tick. Easy fix..new head gasket..all good for a year now..maybe this will help..

The engine might have been switched out because when the dealer runs my Vin it comes back to a 350. I read the engine plate and it clearly says...EM6 237...manufactured in 1982. Kinda sucks that the original engine was swapped out....it is what it is. I'm just learning about these Macks...just gotta fix the tapping noise. Bob

No jake on this truck...yet. I've never adjusted the valves on a diesel. I have done so on older Chevy 350. Is it the same procedure? Valve cover off with the engine running?

Hello all, I'm new to the site .. thanks for having me. I've owned an 86 R 688ST for 5 years now. It's been converted to a fuel truck by the previous owner. It has an EM6 237 engine with a 10 speed transmission. The truck has been used as a storage tank for my diesel fuel. I have the bug in me to get her going again. The engine starts and runs. I have taken her out in the past week for a few 30 minute drives. I changed the filters and oil. Here''s the issue...I think she has a stuck exhaust valve. I can hear a tapping sound at low idle. It seems to go away (or I can't hear it) when I increas