Normal "RPM" for an Isuzu diesel?

[brewer00]

We just picked up a 1982 diesel 280 and being new to the diesel engine I was curious what RPM I would expect to run @ 55mph. I'm assuming that it has a stock transmission and we are running around 3000 RPM. It seems/feels like I should have another gear and seems a bit high as my tach only goes to 4000.

Thanks much,
Matt

[bkahler]

Originally Posted by brewer00

We just picked up a 1982 diesel 280 and being new to the diesel engine I was curious what RPM I would expect to run @ 55mph. I'm assuming that it has a stock transmission and we are running around 3000 RPM. It seems/feels like I should have another gear and seems a bit high as my tach only goes to 4000.

Thanks much,
Matt

Matt,

The first thing I would question is the tach. The tach on our gas 310 motorhome is extremely flaky. I've been meaning to replace it but haven't had the time. What I would suggest is getting an independent verification that the tach is working properly.

Just a thought.

Brad

[cooperhawk]

On our 1985 345 3000 rpm yields 67 mph. It governs out at 3250 and that is 73 mph.

[brewer00]

I'll check the tach but it sure sounds like 3000 RPM @ 55. I would have figured it to be close to the Gunner's findings.

Thanks again..