Isuzu Diesel

islandvu3@cox.net · 03-18-2002, 08:59 PM

I have a 1983 classic 31ft motorhome that does not have enough power. It will only run 61MPH on flat ground and it is hard to get it to that point. I have changed the fuel filters, several times, air filter. I use injector cleaner, so don't think my injectors are dirty. It also runs hot when it works hard on extreme grades. The boost only goes to 7.5 lbs--thats all I can get out of it. Exhaust temp runs 1000-1100 degrees. Do the injectors have a filter inside of them? This is my second deisel motorhome and this one does not run like the 1982 airstream. this is the same basic motorhome only difference being the length. The 1982 would run at 78MPH and this one is lazy--what puzzles me is the boost and RPM. can anyone help me? South Dakota is looming on the horizon.

PeterH-79MH · 03-18-2002, 09:37 PM

Welcome aboard!
There is a member on this board, LKappenman, who has 31' Diesel and experienced similar problems.
Try to contact him by going to the members list on the top of this page, click letter L and then on his name, to send him an email.
Maybe you could continue a good thread on Diesel MHs?

FrankR · 03-19-2002, 08:14 PM

All devices are not created equal. This is very true for the mechanical world. Nearly no two cars, trucks, or motor hames will operate exactly the same under the same conditions. In many cases the power, economy and longivity are determined by checking for the optimum adjustments and tweaking to get everything just right. Most engines run so well that the ultimate tune condition or performance equiptment is included. There are many areas to check. In diesels, the requirements are the same as gas with no spark to consider. Diesel engine performance can be improved with unobstructed intake and exhaust, turbo and larger turbo, increase injection pump fuel delivery and advance pump timing. All performance modifications MUST be monitored. Power is HEAT which must be observed. A pyrometer is a must with a trans temp gage. Removing any exhaust restrictions, and increasing pipe size, is the cheapest instant power increase. As power increases, the heat increases as well. The trans should also have some attention with a shift kit, trans program, increase oil pan capacity, in line exterior oil filter, oil cooler relocation and maybe fan forced cooling. Many performance oriented folks used only all synthetic auto trans fluid. The torque of a diesel engine can be very very high. It may take some relearning. A single 3 inch exhaust will flow more volumn than dual 2 inch exhaust. All 5 inch exhaust with no muffler or cat turned down before rear axle is the best flow for diesel performance, power and economy. When there is lots of power all the throttle is not needed???. Frank Idaho

FrankR · 03-19-2002, 08:22 PM

A picture of our bus repower and auto trans install. This will be great to pull the Kand Yacht... Frank

PeterH-79MH · 03-19-2002, 08:37 PM

I want to sit on the side of the road, when Frank goes by.
A greyhound pulling a 31' Land Yacht

Only in America!

FrankR · 03-19-2002, 08:46 PM

Hey, wait a minute....... The bus is just 36 feet and the Airstream is 31 feet. That is great, as the limit is 70 feet over all. Let's see the power would be there and lots of everything. I posted the idea as a little humor but I think it can be done........ Fran

LKappenman · 03-20-2002, 11:48 AM

We had the exact thing on our 310 Turbo Isuzu for 7 years we love the coach but when we headed back to South Dakota and pulled those passes no power and heating up. No problem on the flat lands . A couple of months ago we took it to a place near Seattle and had them check it out. They first increased the fuel pressure and checked out obvious things that barely helped, then we took it back and they cleaned our injectors they were bad they were low on pop off pressure and the spray pattern was bad,(the previous owner who bought the coach new did not know there were two fuel filters) we also had them adjust the valves while they were in there. Then they found we had bad intake manifold gasket. They tightened the alternator belt and hose clamps that were leaking coolant. We had more boost bay 2-3 pounds making it 12 but still high on the exhaust temp we found we had a bad Pyrometer Guage changed that a wow what a differance.
Regarding the over heating it never did when we were on the flats of small hills only on the long pulls. After talking to the people at Expert Deisel.com they said that probably it was "airflow management" he asked if we had a schroud over the fan No, do we have a fan clutch no, those were recomendations he had also not to the the anti-freeze water mix over 40-60. We had previously re done the radiator.
Our next project is to put on the Gear vendor under/overdrive. But we are very happy with the performance now. LKappenman@aol.com

stuart1 · 10-28-2002, 11:53 AM

Good stories all! I also have the Isuzu turbo Diesel but I need to replace her radiator cap however, the old one doesn't have the PSI written on it. Does anyone know the correct PSI rating to use?...Thanks..Stuart 3052