I’ve got a bit of a problem with my Foden 8 wheeler.
It’s a 450 CAT but there seems to be a problem with the turbo or intercooler. The turbo doesn’t seem to boost until it gets to 1700rpm which is well past the green band. When it does, you can definitely feel it. It’s very flat though before that. I have checked the turbo and the impeller spins freely and there is no play in it.
It has been on the CAT diagnostics and everything is set up correctly. The boost pressure is correct at the 1700rpm.
The way it is running makes me think it could be an intercooler issue. I know when an intercooler is cracked you would here noise, but you don’t hear anything obvious in this case.
Any advice or any pointers would be handy. Or any Foden experts in North London or Hertfordshire can spare any time.
I’ve got a bit of a problem with my Foden 8 wheeler.
It’s a 450 CAT but there seems to be a problem with the turbo or intercooler. The turbo doesn’t seem to boost until it gets to 1700rpm which is well past the green band. When it does, you can definitely feel it. It’s very flat though before that. I have checked the turbo and the impeller spins freely and there is no play in it.
It has been on the CAT diagnostics and everything is set up correctly. The boost pressure is correct at the 1700rpm.
The way it is running makes me think it could be an intercooler issue. I know when an intercooler is cracked you would here noise, but you don’t hear anything obvious in this case.
Any advice or any pointers would be handy. Or any Foden experts in North London or Hertfordshire can spare any time.
Thanks in advance.
Ben
I had a MK2 Alpha with an M11 in it. This had no go in it and this was due to a cracked intercooler. We pressure tested the intercooler by taking off the in and out hoses and blanking them both off. One of the blanks had an in put for an airline, and when we pressurised the intercooler and then turned off the air supply the pressure instantly dropped, but you could not hear the leak. There was a crack in the alloy casting. I probably still have the plugs we made up.
bd85uk:
Was that showing the same symptoms? Could you feel the boost after a certain rpm?
Sorry can’t really remember as it was about 7 years ago. All I can remember is that it was very flat and had no real acceleration when solo. Once we changed the intercooler it accelerated away very quickly.
The intercooler does sound a likely candidate as the higher boost at higher rpms will overcome the leak and then you will feel the effect of the turbo, at lower boost it will leak out before it gets through the intercooler and will feel as flat as a pancake.
It’s always best to start with easy and cheap things and the easiest thing to check is the intercooler, you can make your own test kit for about a tenner, you need two plastic drain pipe end caps the same size as your inlet and outlet on the intercooler, a couple of jubilee clips and a tyre valve. Drill a hole in one and fit the tyre valve in it, put them at either end of the intercooler and inflate to around 30psi and watch for the pressure drop in 20seconds, if it’s more than a couple of psi, chuck the intercooler in a skip.
If that’s all good the problem may be on the fuel side, so check fuel pressure, change filters and check the housings, I know the C15 had a weak water seperator housing and that was causing a drop in fuel pressure.
The valves may also be out of adjustment and the difference between an engine with properly set valves and one that’s out of whack is night and day.
Failing that, join an American truck forum, there’s thousands of CAT owners on those and they’ll know all the tricks.
Well thanks for the help so far. I’ve changed intercooler but has made no difference.
Is there a turbo boost sensor on the c12? I see two sensors in the top of the manifold, maybe it’s one of them?
Also, I’ve been told the inlet manifold gaskets give way. Could that be anything to do with it?
Did you check the new intercooler for integrity? Unfortunately some leak from brand new. On the intake side you could do a smoke test to check for leaks throughout the whole system, if there’s any leaks anywhere from turbo to manifold that will find them, you can usually put the smoke in through the cold start injection port. Car garages may have a smoke tester as they use them to test vacuum systems, like central locking on older cars.
Does the C12 have a wastegate turbo? That could be the problem, if the actuator is playing up it will be blowing the boost straight into the exhaust.
I’ve known of 2 c12’s (1 was in a 4000 foden and the other was in an alpha) where the problem has been with the accelerator pedal which was faulty/worn, though on one of them the problem was intermittent, some days it went well and on another it was very flat
I’d have a look at all the air hoses. It’s not unknown for hoses to delaminate internally and restrict airflow. Then you only get near the required air at higher boost pressures. It’s worth whipping them off, and having a look at the insides.
The same applies to rubber fuel lines, you get internal swelling and fuel restriction. but I’d check the air side first as it’s easier and cheaper. The throttle position sensor shouldn’t affect boost, but with all the electronic conversations between components now I wouldn’t rule it out, it’s another cheap fix and is a 5min job to replace.
Well that was the culprit. Managed to get a cheap second hand turbo and everything is back to normal. You couldn’t see the cracks until the turbo came off. Apparently it is a common problem for CAT turbos to crack.
