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Mack E6-350 help needed

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d9gdon

Senior Member
Joined
Feb 12, 2010
Messages
1,517
Location
central texas
I've got an E6-350 in a '90 model CH613 tandem axle dump that doesn't have much power, never has since I bought it. I've had the engine overhauled and the injector pump rebuilt in the last 9 months, mechanic didn't see anything causing it, course I was in a hurry to get it out of the shop. I figured I could find the problem on my own. I replaced the turbo before the overhaul.

This has been an ongoing headache for a while. I'm only getting about 18-19 lbs of boost at the manifold (checking it where the puff limiter is plumbed into it). I think I saw somewhere that it should be 22-25 lbs. I've changed fuel filters several times, air filter, put in fuel conditioner. The injectors were tested at overhaul. Checked the throttle cable, it's working right.

I'm wondering about the fuel pressure now, maybe the transfer pump is bad or the suction line is plugged partially. What should it be at the injector pump and where's the best place to check it?

Wondering what else could be causing it.
 
willie59

willie59

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Haven't worked on many Mack engines, don't know what components they use. Does your turbo have a waste gate valve on it? Injection pump have an aneroid valve on it? Aneroid valve could have a busted diaphram, unlikely though, seeing you have the pump rebuilt. But if you have a waste gate valve, make sure the diaphram in the pot isn't busted, that will vent your boost pressure.
 
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dist3

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Mar 23, 2008
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Connecticut
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Equipment Manager Enviromental and Site Contractor
How many hours on truck engine?
 
heavylift

heavylift

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Sep 5, 2009
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KS
I would check the pressure....
some older fuel lines can go bad and crack internally causing a flow problem
maybe a pinched fuel line restricting flow....

good luck



we had a new 80 international that when they built it... the protective cap was left on a fuel line... it would use out of only one tank.... but of course the return was to the tank it wouldn't empty...
they replaced every fuel line on the truck still the same... the plastic cap was stuck in the threads on the tank... which they finally found when they was inthe process of putting a new fuel tank on it.... It was at least a one month in the shop job
 
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d9gdon

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Joined
Feb 12, 2010
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Location
central texas
I'm wondering about the fuel pressure now, maybe the transfer pump is bad or the suction line is plugged partially. What should it be at the injector pump and where's the best place to check it?
Click to expand...

Right, that's what I was asking.
 
I

imbzcul8r

Member
Joined
Oct 3, 2008
Messages
22
Location
B.C. Canada
Do you have an air to air intercooler in front of your radiator? My guess would be you do, you should take a good look at all the connections between the turbo, air to air cooler & intake manifold as well as the cooler itself. I ran quite a few of the E9 v8 macks and it was fairly common when they got older for the intercooler to crack, they were aluminum & vibrations & too many miles would break them up. Most times you couldn't hear it leaking turbo pressure from the cooler, but if it was one of the silicone hoses between the turbo & cooler & back you usually could hear it hissing. Cooler leaks are harder to find, you can take it to a rad shop & pressure test it, or if you're getting any oil from your turbo sometimes you will see oil signs coming out of the cooler. The engine might also smoke a little more with the cooler leaking, but if your puff limiter is bypassed you probably can't tell, they were pretty smoky old engines anyway.
 
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d9gdon

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central texas
Yeah, it's got the air to air aluminum aftercooler in front of the radiator. I changed all the hoses to and from it thinking one of them might be leaking. I had one clamp come loose one day before that and it squealed real loud.

I'll look and see if I can figure out a way to pressure test it with air on the truck, if not I'll take it off and run it over to a radiator shop.

thanks
 
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Greg

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Jan 28, 2008
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Wi
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Excavating Contractor
You may want to change the relay which controls when the turbo starts kicking in. Had an E6 300 with no guts the same as yours. Changed the reversing relay which got the turbo on line at lower RPM and it made a whole different truck out of it.
 
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macka80

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Apr 27, 2010
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1
Location
Cromwell New Zealand
mack problems

hi there im not sure if youve checked the fuel tank breathers because ive found that the problem a couple of times when it pressurizes it restricts the fuel flow. cheers
 
O

Oldiron

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Dec 18, 2009
Messages
52
Location
Alberta Canada
Have you tryed unhooking the air line at the pufflimiter cylinder on the pump, If the injection shop put the wrong cylinder on or it is shimmed wrong you won't get full fuel , the pump shop doesn't usuallly have the cylinder pressurized when they bench test the pump, the other thought is does your fuel stop move all the way and have you checked the breakover for full travel and a strong enough spring , I know these are simple things but sometimes.......:beatsme
 
W

Willis Bushogin

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Nov 6, 2007
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855
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NC
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owner
power

d9gdon said:
Yeah, it's got the air to air aluminum aftercooler in front of the radiator. I changed all the hoses to and from it thinking one of them might be leaking. I had one clamp come loose one day before that and it squealed real loud.

I'll look and see if I can figure out a way to pressure test it with air on the truck, if not I'll take it off and run it over to a radiator shop.

thanks
Click to expand...

This can drive you nuts I think I listed this in another post, but I bought a truck with a Cat 3306 in it and it took forever to get to 60mph
air cooler pressure checked
boost pressure checked
aneroid changed
injection pump replaced
fuel pressure checked
finally turbo checked again, when you try to turn it backwards it would bind up, replaced the turbo and got the power it should have. But the 3306 or the E6 it not a power house.

New power issue, another truck, driver complained about truck was losing power
changed fuel filters
changed air filter
changed transfer pump
changed fuel hoses
Then the mechanic got smart and put a fuel pressure guage on the system and it only had about 10-15psi. We put the intake fuel line in a fresh can of fuel and we had 40 psi pressure. HUMMMM, drained the tank and removed it an found a shop rag in the tank Removed the rag and everything OK

Put a fuel gauge on the fuel filter closest to the engine, it should be a plug that you can remove and install a gauge
Good Luck
 
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d9gdon

Senior Member
Joined
Feb 12, 2010
Messages
1,517
Location
central texas
Found the problem

Runs totally different now. I unhooked the airline from the reversing relay on the intake that goes to the front of the injector pump and plugged it off.

It really runs good now. I can't believe what a difference it made.

Thanks to everybody, now it's not such a pain to drive anymore.
 
S

sparky727

New Member
Joined
Oct 29, 2010
Messages
1
Location
Warren, PA.
e6-350

I have another question about the E6..we replaced the heads with re-done ones..same heads just fresh..problem is now oil seeps out of the second exhaust port..I was told the rings were bad then was told it was a valve guide..how do I tell which thing it might be..there is no oil coming out the valve cover vent ,and there is no black smoke out the exhaust stack when idleing
 
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McLizard

New Member
Joined
May 23, 2011
Messages
1
Location
Antarctica
Oil leakage around exhaust ports

Hi,

Is it a 350 4 Valve? If so the exhaust studs need to be sealed with something like loctite thread sealant or similar when installed into the heads. You can do this without removing the manifold by doing only the effected stud/studs. I have seen a lot of people think this is oil coming from the cylinders. Sometimes in the machining process the threads partially go through into head cavity.

Do you want to know the correct way to set up your puff limiter reversing relay and the ram that is on the injector pump? If so let me know. I worked for MACK for 20years and know the systems well

Hope this has helped :)
 
T

tctractors

Senior Member
Joined
Oct 9, 2007
Messages
2,412
Location
Worc U.K.
A simple way to test the Intercooler is to remove and fill it with parafin (Keroseen) any leaks will show up fast, plus it gets a good flush out,to test the air fuel ratio control, remove the pipe from the inlet manifold and set it so you can blow down the pipe,if your eye balls start to pop out things are good, if its like blowing down a straw, there is an air hole some where from your mouth forwards to the AFRC, often the intercooler is linked to the turbo and manifold via alloy pipes if so also remove the pipes and check for holes and cracks, some truck engines in the U.K. have bits of gear stick bolted to the inlet manifold resulting in damage and cracks after a few years.
 
B

Blue Rd

New Member
Joined
Apr 1, 2016
Messages
3
Location
Ontario
E6 350 puff limiter. Need more info please

Need more info
McLizard said:
Hi,

Is it a 350 4 Valve? If so the exhaust studs need to be sealed with something like loctite thread sealant or similar when installed into the heads. You can do this without removing the manifold by doing only the effected stud/studs. I have seen a lot of people think this is oil coming from the cylinders. Sometimes in the machining process the threads partially go through into head cavity.

Do you want to know the correct way to set up your puff limiter reversing relay and the ram that is on the injector pump? If so let me know. I worked for MACK for 20years and know the systems well

Hope this has helped :)
Click to expand...
 
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