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High Exhaust Pyrometer Temperature.low Power


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Hey everyone,I've got a problem with my E9 running a high pyro temp.Had the truck for 15 yrs. so i know it pretty well,or at least i thought i did.I sat it around for about a year,and now that i want to work it again its giving me grief,isn't it always the way.It used to run around 400-420 celsius on the pyro,but lately it,s up around 530-550.celsius, and it would'nt pull a sausage around a greasy frypan.Ive pressure tested the lift pump.40 psi. at idle-55 psi.at 1500rpm.Took the turbo, which has only done 90000km. since i rebuilt the engine,off and had it checked again and was told it was perfect.Checked all the usual stuff,air-inlet restriction,air cleaner element,exhaust restriction,spun on some new fuel filters etc.all to no avail.Put a new anneroid valve and puff limiter piston on and played around with the shimming till it seemed to be working properly, but more fuel just meant a higher pyro temp.This thing is doing my head in.I pressure tested the intercooler,and i am losing pressure in a static test.Duralite say if you lose more than 5psi.over 15 seconds at 30 psi pressure,you have a problem.I tested it by blocking the intercooler pipe where it goes into the turbo on the pressure in side so it would show up any inlet manifold leaks as well when soapy water was sprayed on it.No leaks in the manifolds anywhere,but a decent leak from the front and rear of the top left corner of the intercooler.Not stone damage,more like cracking where the tubes meet the side tanks.It loses about3-4psi over 15sec.My question is,does this static leak have the potential to take away a heap of power and send the pyro through the roof when the truck is being worked and everything heats up?

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Hey everyone,I've got a problem with my E9 running a high pyro temp.Had the truck for 15 yrs. so i know it pretty well,or at least i thought i did.I sat it around for about a year,and now that i want to work it again its giving me grief,isn't it always the way.It used to run around 400-420 celsius on the pyro,but lately it,s up around 530-550.celsius, and it would'nt pull a sausage around a greasy frypan.Ive pressure tested the lift pump.40 psi. at idle-55 psi.at 1500rpm.Took the turbo, which has only done 90000km. since i rebuilt the engine,off and had it checked again and was told it was perfect.Checked all the usual stuff,air-inlet restriction,air cleaner element,exhaust restriction,spun on some new fuel filters etc.all to no avail.Put a new anneroid valve and puff limiter piston on and played around with the shimming till it seemed to be working properly, but more fuel just meant a higher pyro temp.This thing is doing my head in.I pressure tested the intercooler,and i am losing pressure in a static test.Duralite say if you lose more than 5psi.over 15 seconds at 30 psi pressure,you have a problem.I tested it by blocking the intercooler pipe where it goes into the turbo on the pressure in side so it would show up any inlet manifold leaks as well when soapy water was sprayed on it.No leaks in the manifolds anywhere,but a decent leak from the front and rear of the top left corner of the intercooler.Not stone damage,more like cracking where the tubes meet the side tanks.It loses about3-4psi over 15sec.My question is,does this static leak have the potential to take away a heap of power and send the pyro through the roof when the truck is being worked and everything heats up?

sounds exactly like what the '77 300 Mack I drove would do when a little short piece of hose would split, letting the turbo "suck air". I carried a piece of heater hose with me and had to replace that hose on the road several times. It was a small hose, about 5 or 6 inches long. I know nothing about a V8.

Producer of poorly photo-chopped pictures since 1999.

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Hey everyone,I've got a problem with my E9 running a high pyro temp.Had the truck for 15 yrs. so i know it pretty well,or at least i thought i did.I sat it around for about a year,and now that i want to work it again its giving me grief,isn't it always the way.It used to run around 400-420 celsius on the pyro,but lately it,s up around 530-550.celsius, and it would'nt pull a sausage around a greasy frypan.Ive pressure tested the lift pump.40 psi. at idle-55 psi.at 1500rpm.Took the turbo, which has only done 90000km. since i rebuilt the engine,off and had it checked again and was told it was perfect.Checked all the usual stuff,air-inlet restriction,air cleaner element,exhaust restriction,spun on some new fuel filters etc.all to no avail.Put a new anneroid valve and puff limiter piston on and played around with the shimming till it seemed to be working properly, but more fuel just meant a higher pyro temp.This thing is doing my head in.I pressure tested the intercooler,and i am losing pressure in a static test.Duralite say if you lose more than 5psi.over 15 seconds at 30 psi pressure,you have a problem.I tested it by blocking the intercooler pipe where it goes into the turbo on the pressure in side so it would show up any inlet manifold leaks as well when soapy water was sprayed on it.No leaks in the manifolds anywhere,but a decent leak from the front and rear of the top left corner of the intercooler.Not stone damage,more like cracking where the tubes meet the side tanks.It loses about3-4psi over 15sec.My question is,does this static leak have the potential to take away a heap of power and send the pyro through the roof when the truck is being worked and everything heats up?

The pyro heating up indicates not enough air yes the leak has alot to do with it!

BUT was this problem there when you changed out the turbo before?The turbo can look and feel fine but if thr wrong compressor wheel was installed at rebuild it will get warm!

Check the gap around the compressor wheel if it has a big gap say 1/32 of an inch its got the wrong wheel on it Ive see this happen on rebuilds before.

just somthing else to look for.

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Thanks for your interest everyone.I'm unable to give an accurate idea of boost pressure as the truck hasn't got a boost gauge.I did however run a test in which i attached a pressure gauge to the inlet cross-over manifold at the rear of the motor.when i roadtested the truck,i loaded it up by holding it back on the footbrake and putting the throttle to the floor to try to simulate a loaded condition.The gauge only read 2psi maximum and under non loaded-up driving my assistant said it actually had vacuum.He said he was hoping to get a reading of at least 15psi.Was that an appropriate location for the pressure gauge to fitted or should it be on the intercooler ducting? Iv'e done a lot of pressure testing on the intercooler side of things but thev'e been inconclusive.maybe under on-road conditions when everything is hot it gets worse.the turbo was reco-ed when the engine was rebuilt by my local mack dealer.all genuine parts where used apart from the valves,guides,and seats which were Pai parts as the genuine parts are way too dear when your talking 4 valves per cylinder x 8.What sort of boost pressure should i see if it was running properly?The truck used to pull like a freighttrain before i stood it down for 12 months.One thing i did notice when i got the truck back after the rebuild was the turbo used to whistle back through the exhaust like a scania on gearshifts.At the moment your'e battling to hear it whistle at all.The turbo company bench-checked it the other day and insist that its ok.I suppose if the intercooler leak is bad enough the turbo woundn't whistle because its got no pressure on it.Any thoughts are gratefully recieved,thanks guys.

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Thanks for your interest everyone.I'm unable to give an accurate idea of boost pressure as the truck hasn't got a boost gauge.I did however run a test in which i attached a pressure gauge to the inlet cross-over manifold at the rear of the motor.when i roadtested the truck,i loaded it up by holding it back on the footbrake and putting the throttle to the floor to try to simulate a loaded condition.The gauge only read 2psi maximum and under non loaded-up driving my assistant said it actually had vacuum.He said he was hoping to get a reading of at least 15psi.Was that an appropriate location for the pressure gauge to fitted or should it be on the intercooler ducting? Iv'e done a lot of pressure testing on the intercooler side of things but thev'e been inconclusive.maybe under on-road conditions when everything is hot it gets worse.the turbo was reco-ed when the engine was rebuilt by my local mack dealer.all genuine parts where used apart from the valves,guides,and seats which were Pai parts as the genuine parts are way too dear when your talking 4 valves per cylinder x 8.What sort of boost pressure should i see if it was running properly?The truck used to pull like a freighttrain before i stood it down for 12 months.One thing i did notice when i got the truck back after the rebuild was the turbo used to whistle back through the exhaust like a scania on gearshifts.At the moment your'e battling to hear it whistle at all.The turbo company bench-checked it the other day and insist that its ok.I suppose if the intercooler leak is bad enough the turbo woundn't whistle because its got no pressure on it.Any thoughts are gratefully recieved,thanks guys.

Al

the boost gauge was plumbed in the right spot the cross over is where to do it!You should be seeing 22 to 28 psi under a decent pull!

You either got one hell of a leak or the turbo is not working right you should be trailing plumes of black smoke behind ya if theres a leak that big.

Is the fuel pump robert bosch? if you don't have smoke .I would check the lda valve on the back top of the pump take the hose off at the engine end and suck on it

if it will not hold a vacuam the diphram inside is fubar.

Also if the engine has an air throtle make sure the dam thing is opening right up!

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Hi Al and everybody, Does your Air Compressor intake come from the manifold? I had an E6 that had a split in that little intake hose and it used to open up under pressure when it got hot, and send the pyro up. Regards - Michael.

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Greetings all.Thanks for your ideas and possible causes.I hope that iv'e narrowed it down now to the intercooler.Most intercoolers lose a bit of pressure and thats what threw me,because when i did a static test the leak wasn't too bad,but i'm willing to bet when everythings hot that leak will open up,and there goes my boost pressure. Fullfuel asked if it was trailing smoke,and if it increased under load,and it definetly does.Kav from oz,it picks up it's comp.air from the intercooler pipe near the flange joint so i'll replace that pipe for sure,its probably as old as the truck and stiff as a board so that's good tip.We rigged up a pretty rudimentary boost tester with a rubber hose out the window down under the cab to the inlet cross-over and that's what convinced me.Fjh said it should have shown at least 22psi or more and the best reading we could get was 2psi.My assistant is a workshop foreman at my local mack dealership and he's someone i trust implicitely and it would be easy to say he should have picked it up,but there's not that many people around that know these older engines so i'm not going to get upset about that.He said he expected to see at least 15psi and couldn't understand the low reading,but i had given him my assurance that the intercooler leak wasn't that bad.Fjh also asked if i was getting full travel on the throttle at the pump.Its a mechanical linkage and it's opening right up.How did anyone drive these things with an all or nothing Williams throttle? Once again everyone,thanks for your help.I'll let you know how it turns out and whether wev'e nailed it.

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you dont have boost! 22 psi is a low side I think 25-30 would be what you shoul see. My straight 6 285 will pump out 28-30PSI in the cold. this is with the pump turned up a little.

Trent two diffrent animals!22- 28 is spec on a v8 A good hot runing v8 500hp will be 28 -32 I beleive his is a 400!A 400 I would expect to see 22 24 maybe 25 max!If the fuel is stock!

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Trent two diffrent animals!22- 28 is spec on a v8 A good hot runing v8 500hp will be 28 -32 I beleive his is a 400!A 400 I would expect to see 22 24 maybe 25 max!If the fuel is stock!

10-4 fred.

The 440 V8 at the yard holds around 26-28PSI. I think its a 1991 model? on a good pull I figured it should be close to that psi?

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