Maiden voyage for towing with the PSD. 99 PSD 2wd. I towed my blazer from pheonix to tucson which is about 100 miles, all flat territory. I towed without using overdrive and it seemed to tow rather nicely except the tach showed about 3100 to 3200rpms doing about 70-75mph (4:10 gears). My question, can these engines take this kind of rpms for a prolonged period of time. Next question, about every other minute i would here something kick on, kind of like a vacuum cleaner (but not as loud), Could this be the fan kicking off & on or the turbo perhaps. The truck is new to me and have very little knowledge of them. Thanks for your time Joe
Yikes!!!! That is almost redline. I would not recomend those RPM's Leave it in OD unless it is shifting in and out...on hilly ground. Flat you should have no problem. That is the clutch fan kicking in....the turbo is just the whistle. If you do a lot of towing or doing any performance up-grades i would buy a good set of gauges...pyro, boost, trans temp.
Whoa!!! Try not to do that again!!! Leave that bad boy in OD! Your exhaust gas temps must have beeen sky rocketing. The 7.3 is not a high revving engine like the 6.0 is. You should only switch out of overdrive when going up hills and down very steep grades. I bet you only got about 6 mpg. You can easily pull 6 blazers on flat land in OD doing 70mph at 2000 rpms.waytogo
acually the temps where not bad, as a truck lugging the motor will have more EGT than one reved out. i tow in 3rd ALL the time.... i like to keepo it under 2,800rpm, i usually cruise at about 2,500. larger trucks with allisons with the larger cam(aka lower rpm) are ALWAYS running 2,500-2700 and they last 250k all the time.
Thanks for the replies guys. Glad I posted this thread. In time, I will add some gages just to know what the engine is doing instead of guessing. Yea, got real bad fuel mileage. I've read several posts saying not to tow in overdrive. Guess I misunderstood, or it was not clear when to use OD. Thanks again Joe
I have to disagree with you. What makes the egts go up is the fact that all that fuel is being burned and the forced air flow is high and dense. As to how you tow, we all have our own towing habits and we do whatever works. cruising at 2500 rpms is pretty normal, but 3200 is getting close to where the engine will defuel at. Most of the big (highway)trucks run 3.55's, at least the ones around me, therefore enabling the motor to run at lower rpms. and they also have better than 10 gears. As for our trucks, we only have 4. 250k for a well kept diesel should be only the beginning. Although diesels arent indestructable! , you have to treat them right or like anything you mistret, it will fall apart or wear out prematurely. High revving will cause you to have to rebuild that motor quicker.(speaking of the 7.3 as it is a low revving motor) The newer diesel are high revving motors.
tell me which has higher EGT 2100 Rpms pulling 15 k, or 2,800 pulling 15 k at the same speed? the 2100 rpm has more egt, as you are lugging the motor and not keeping it in its powerband.......... the 7.3L is a higher revving engine compared to most others. hell, my l10 cummins i run to around 2,700 all the time and rev it out like that to do 72mph where it tops out, and thatws got 10 liters of fury. also rev out the 8.3L pretty good near its max when cruising 74mph. i would rather over rev a motor a tad than lug it, as the lugging creates LOTS of extra load, and harm to the engine, you can also hurt cranks very easy on some cat motors by lugging them......
I agree w/ burnedbronco, I has a 95 dodge 12 valve and when I made a run at the hill with a load, the EGT's were alot cooler at 2500 rpm in 4th than at 2100 rpm in 5th. trucks are governed and can run at 2800 to 2900 rpm all day and all night.
EGT's will be higher at lower RPM's than high RPM's. Reason is air flow, lots of air flow through the engine and turbo at higher RPM's. This is what I have come to undertand.waytogo Original poster, About OD, generally with a gas truck you want to try and keep it out of OD. With a diesel pickup that is harder because of what you experienced, the diesel likes to be down lower and not revved up. With the older trans like yours and mine, it is harder on them to be ran in OD because it will want to run warmer, but you don't want to over rev the motor either. I usually let the truck decide, keep the OD button on and if the truck wants to shift into OD and stay there, I let it.
I don't think he's pulling enough weight to worry about EGT issues. I've pulled my 12,000LB 5er down the hiway (in OD) with the Superchips in the race setting and had no problems with temp. I did have a problem pulling a 6% grade though!! I usually leave it in OD till it starts to lose speed and then kick it out of OD to pull the hill. Use the OD button. That will keep the trans locked in 3rd, get the RPMs up and help keep the EGT down. More air in = more air out and that helps keep EGTs lower.
