So, I bought a 97 580L with the 4-390 engine. Seems to run fine on flat ground. Might be a little underpowered heading up a hill in second gear but I attributed that to the fact that it's not turboed. It smokes a little when I first start it up but after a few seconds that goes away. I was used to that with both my other diesels. However, when I'm going downhill, such that the machine is up over 2000 RPM, I have white exhaust coming out...with a STRONG smell of diesel, which suggests to me that it's fuel, not coolant. But it only does it heading downhill under load, not a whiff of smoke when it's floored going uphill. Any suggestions? The machine supposedly was a one-owner with only 2300 hours on it.
Air in your fuel somehow, check the filter, any rubber lines, fittings etc. Maybe pressurize your tank a few PSI and see if anything drips. Possibly an injector? or timing? That pretty much covers all the bases, you don't have to convince me that it's not coolant, you'd see it missing soon enough if it was blowing that much coolant. I'd probably use a temperature gun to check the exhaust manifold to see if any cylinder is hotter, or significantly cooler than the others, if not, use your favorite snake oil and run it hard.
Thanks for the reply Delmer. I'll look for a fuel leak and I'll grab a temp gun next time I'm in town. I just thought that it was odd that it only did it when the engine was holding the machine back.
That is the key, only smokes with the throttle shut under engine braking. This narrows it down to excess fuel coming from a leaking injector OR pulling crankcase oil under engine braking. If a leaking injector temp gun will show normal, if bad rings, it should run cooler under load for that one cylinder. Howard