I drive a 2006 Volvo, with a 475hp ISX Cummins, and 18-speed gear shift. A few days ago, when I started out in the morning, the engine sounded a bit different, a bit ragged at times, and the usual high-pitched whistling sound of the turbo, was missing.

I started out with an empty trailer, ran for about 60 km, switched to a loaded trailer at the customer's site, and after running for about 25km, when I started to go up a grade, I had to downshift drastically. On prior occasions, I've negotiated that same grade by dropping a gear, from 8.5 to 7.5....but this time I had to drop to 4, and when I looked at the turbo pressure, there was barely any, even going up the grade. I reached the conclusion that there was something definitely wrong, most likely with the turbo, and managed to limp it to a nearby Petro Canada truck stop. From there, I got in touch with my shop, who sent out a tow truck, along with a replacement truck for me to complete the trip.

Since my truck is under warranty, it was taken to Volvo, where, after 2 days, they said that they could find nothing wrong with the truck, much to my astonishment. Currently, it's back at the yard, and I've been asked to switch back to it from the replacement truck.

Could any of you surmise on what could possibly be the problem, and why Volvo gave a clean chit to the truck ? Thanks in advance.

 

If the boost pressure is just about nonexistent and it has low power there is obviously a problem with the turbo, or a major leak in the piping or charge air cooler.

When the ECM does not see sufficient intake manifold pressure, it will not allow the engine to get full fuel when you push the throttle to the floor.

Why the dealer would say there is nothing wrong with it, given the low boost condition is a mystery to me.

 

EGR valve

 

What exactly does the EGR valve do, and in what way, in your opinion, could it be causing the problem ? Thanks

 

The EGR valve opens and closes, controlling how much exhaust flows from the turbo manifold(before the turbo), into the engine inlet.

Very common problem on the ISX engines. Usually you'll see a huge puff of black smoke when you shift, the engine wont make boost, and it will be GUTLESS.

Because it's open, the turbo cannot do its job.

 

Thanks for that, Allan. What really surprises me, is that the guys at Volvo said that there was no problem with it, even though it's still covered under it's original warranty.

 

Take it to Cummins.

The Volvo guys may not be familiar with that engine, at least not as familiar as the Cummins mechanics who work on them exclusively.

 

You still need to take it back to the dealer and not another shop. If you don't get a response then ask to speak to the owner. Then make a call to Volvo if that doesn't work. It's there problem, not yours. Make them fix it.

 

Exactly, besides, your engine warranty is with cummins not volvo.

 

He can take it to a any Cummins actory store and they will do the warranty work on the engine. :roll: Why take it to Vulva, where the mechanics have marginal training on all brands of engines when you can take it to the place that exclusively works on Cummins.