clydeps
Member
The problem; Isuzu uses a plastic pipe on the output of the NPS's 4HK1 engine's intercooler, presumably because neither a flexible rubber pipe nor a pressed steel pipe as used in the intercooler inlet is conducive to mounting the manifold pressure sensor which is on the low pressure side of the intercooler.
However retaining a semi-rigid plastic pipe on the intercooler under pressure isn't easy. Isuzu uses a rubber sleeve inside the plastic pipe, clamped behind a rolled bead on the intercooler output tube. This retains the rubber sleeve well - but the plastic pipe has a tendency to slide off the rubber. This is what it looks like when it does:
Notice that the end of the pipe is now distorted - this is probably why I'm told that when it blows off once, it will do so again. That's exactly what happened last week. It came off, we tilted the cab and reattached it, then about 30km later, on a freeway in rush hour, it came off again. Without any boost the engine is gutless - 40 km/h is about the top speed, and any kind of incline reduces it to around 10.
Coincidentally a couple of days before a business on the Gold Coast, CRG, that specialises in turbo manifolds had announced they were making fabricated alloy replacements for this pipe - I was pointed in their direction and ended up calling in to them on Monday. They told me they had sold their entire first batch and also needed to test-fit a variation of the pipe for the more recent (post 2018) trucks. They then suggested that since I had a single-cab truck right there that if I cared to let them test fit their prototype I could drive away with it fitted. So that's what happened and the result is below. So if anyone with an NPS is having the same issue get in touch with CRG - https://www.crgfab.com.au/ or find them on Facebook.
However retaining a semi-rigid plastic pipe on the intercooler under pressure isn't easy. Isuzu uses a rubber sleeve inside the plastic pipe, clamped behind a rolled bead on the intercooler output tube. This retains the rubber sleeve well - but the plastic pipe has a tendency to slide off the rubber. This is what it looks like when it does:
Notice that the end of the pipe is now distorted - this is probably why I'm told that when it blows off once, it will do so again. That's exactly what happened last week. It came off, we tilted the cab and reattached it, then about 30km later, on a freeway in rush hour, it came off again. Without any boost the engine is gutless - 40 km/h is about the top speed, and any kind of incline reduces it to around 10.
Coincidentally a couple of days before a business on the Gold Coast, CRG, that specialises in turbo manifolds had announced they were making fabricated alloy replacements for this pipe - I was pointed in their direction and ended up calling in to them on Monday. They told me they had sold their entire first batch and also needed to test-fit a variation of the pipe for the more recent (post 2018) trucks. They then suggested that since I had a single-cab truck right there that if I cared to let them test fit their prototype I could drive away with it fitted. So that's what happened and the result is below. So if anyone with an NPS is having the same issue get in touch with CRG - https://www.crgfab.com.au/ or find them on Facebook.
