BobDeSoto Posted September 21, 2019 Report Posted September 21, 2019 I was on a Hill and Valley Tour today - 51 DeSoto The brakes started to fade a bit so I used low gear and the engine to slow down on the hills. I could still stop if I needed. Using the engine to brake raised the rpms and caused a considerable amount of smoking. What do you think is the likely culprit causing the smoke? Quote
DJ194950 Posted September 21, 2019 Report Posted September 21, 2019 Valve guides are getting a little too loose which allows more oil to get sucked up into the combustion chamber when on a long deceleration (going downhill using engine as braking. DJ Quote
Dan Hiebert Posted September 21, 2019 Report Posted September 21, 2019 Ditto. Worn valve guides. Quote
John Reddie Posted September 22, 2019 Report Posted September 22, 2019 Back when I was young and had a few Mopar flatheads, they were pretty worn and tired by the time I got them and behaved as you described. Oil pressure was usually pretty low too but I kept topping up the oil and didn't push them very hard and got by okay. Fun times back then. John R Quote
keithb7 Posted September 22, 2019 Report Posted September 22, 2019 (edited) I had the top end of my 265 engine apart 2 years ago. It was my first time in there. I had low compression on two cylinders. I did my first valve grind. The car was new to me. At the time I was not aware of any smoke while engine braking. I wanted to get out cruising, enjoying it. I overlooked the valve guide clearances. #1 exhaust felt a little looser than the rest. I pushed ahead and completed the grind job. I’ve had a great time with the car since then. However, I regret not changing the guides now every time I see the smoke. Which happens on steep declines, regularly. I should have done it right. If you are considering your next move to deal with the smoke, might as well start with a compression, and oil preasure test. Then you’ll know how far you’ll be going into the engine. Edited September 22, 2019 by keithb7 Quote
BobDeSoto Posted September 22, 2019 Author Report Posted September 22, 2019 That's exactly what I was wondering - what to do next. I suppose I already knew! Thanks Quote
oldodge41 Posted September 23, 2019 Report Posted September 23, 2019 It's old enough to smoke if it wants to. I find mine smokes a little less if I run the oil level about a pint or so low on the dipstick. Quote
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