THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

What is a good RPM range for a 710M at highway speeds? 3000? 3500?

that is tough question to answer. Each truck "likes" different speeds and RPM's. My 712 cruises nicely at 61mph but my 710M prefers to cruise under 60mph. I have had the driveline lightened and balanced in the 710 and run the same tires on both trucks. Other trucks in the club have the same results. Some of the 710's will run out very well while other trucks just seem to run out of steam around 55-60.
Basically you have to let the truck let you know where it is comfortable running.

I get what you're saying. With the 710M I had before, it definitely had a "sweet spot." I don't remember the speed or tach reading, though. My current speedometer isn't working, so I'm playing it by ear (literally). It seems to hum along okay at around 3100 RPM and also around 3500. Jeff had suggested not going above 3200. Is that sound advice? I guess my main concern is I don't want to "red line" it on the highway, but there's no red line on my tach, lol.

When I had 33's it ran well at 3100, now I have 31's and it runs at 3500 for the same speed. There are a lot of variables. Might want to get a tach, at least a working speedometer.

Back in the days when my 712W had the stock engine, tranny, and tires, I drove it for thousands of miles at just over 60mph (>4,000 rpm) with no apparent ill effects. This was not short sprints but cross country trips for hours at a time (between fuel stops!). Listen to your truck, it will tell you when it is happy and when you are abusing it. In my experience, cold temps required lower rpms but once well warmed up the rpms could increase. So on a hot day, not only was the driveline drag reduced but the engine just felt like it wanted to run faster.

Thank you guys. This is all good information. I don't think I phrased my question very well, but Jimm's response got to the heart of it. I've got a tach, so I know my RPMs. I've got a speedometer, but it's not in yet. I guess the core of my question was, "What sustained RPM is likely to cause damage?" (So that I could avoid going that high). It's reassuring to hear that 4K isn't going to cause instantaneous combustion. I'll experiment between 3k and 4k and see what feels right. It's been years since I had a Pinz, so at this point it always sounds like I'm abusing it, LOL. I'll get back into the groove. Thank you all, again. Will

My speedo is broken. I use a gps/speedo app on my phone and have a phone holder stuck to windshield. I can also video while driving . A two fer.

Get cylinder head temp gauges and use them. I'd personally consider 3400 redline for continuous running and be much more comfortable at 3200. Jimm391730 running reliably for hours at greater than 4K is amazing though!

Speaking of head temps. I got my gauges running and ran drove for 150 miles on varying grades from flat to 1000ft inclines. 7%

With the overdrive on:
80 F ambient temp
712M
60 mph average
330 to 360 F head temp (sensor under #3 plug) depending on grade
50-60 psi oil psi
125 oil temp (sensor mounted after oil cooler where SAV recommended) I think I need to change this location
3000 rpm
26-28 volts
Air conditioning on
12.56 mpg

Are any of these out of range?

only thing looks wrong is the engine rpm at 3000 for doing 60 mph in a 712

I had installed a full set of cylinder head and exhaust gas thermocouples (cylinder head were the ring under the sparkplug kind) and I really didn't get much information from them; IIRC they stayed pretty consistent when moving. So when they failed in a year or two I never replaced them. Maybe I didn't know what to look for, but when they didn't change much during different driving conditions I felt they didn't add much to my information about the engine. Bikmakr's data reminded me of what little I got from mine.

125 oil temp I mounted my oil temp sensor per SAV location (some years ago) and have never seen temps that low except when parked for a day in the sun. My running temps are consistent between 200 and 230 depending on speed, road grade, outside temp and of course amount of payload.

I suspect something wrong with oil temp sensor/gauge. Anyone else have such low readings?

I know that the former MOZO pinzgauer (now owned by "rmel" on this list) has full gauges for engine temperature including EGT and each cylinder.

Might be good to check with him on what he sees normally.

125 oil temp (sensor mounted after oil cooler where SAV recommended)

This is on the cold side of the cooler; it is NOT oil sump temperatures. My EFI temp sensor is on the hot side of the cooler (required a custom mounted sensor, just below the oil pressure switch) and usually runs about 180-200F, so 125 after the cooler does not seem unreasonable. But I can't think that the cooled oil temperature reading has much value regarding the condition of the engine.