no boost

cab

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Doing some plowing with low horse D8 36A and something seemed wrong with power output. As in load would drag engine down and I'd have to raise plow or throw clutch to keep from killing engine.

Unscrewed plug in center of intake manifold and ran a hose to a liquid filled 0-60 psi gauge where I could monitor it in operator's station. Under load the needle never even moves, just stays on zero.

When killing engine the turbo can be heard to keep spinning after engine stops for 5 seconds or so, which I think is proper. No black smoke noticeable under load as would be expected in an over fuel or under air situation.

Turbo called for is 2M5488. Air cleaner is the older vertical style with the vortex tubes and dust pan.

Opened left brush screen at idle and did not observe exhaust or intake leak. No odd noises other than turbo does make a very high pitched whine while running at higher rpm, but I didn't think that was too unusual. The high pitched whine is sort of heard "in the background", and not overly offensive or siren-like at all. Also my plow is sized appropriately for 8H and cutting edges are new and sharp.

Questions:

Is the threaded plug in center of intake manifold the proper place to check boost?

Should boost be +/- 20psi under heavy load?

Where might I find a 2M5488 turbo and is that what I should be doing or is there other testing or possibly rebuilding options for current unit? Apparently Cat Classic doesn't offer the equivalent.

Thanks for replies!

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Mon, May 30, 2016 3:25 AM

Rome K/G

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Did you check all the minor things? Air filter, fuel pressure up, fuel tank cap breather clean? Thats ok to check the manifold pressure there. Check the fuel filters?

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Mon, May 30, 2016 4:53 AM

cheshire cat

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Reply to Rome K/G:

Did you check all the minor things? Air filter, fuel pressure up, fuel tank cap breather clean? Thats ok to check the manifold pressure there. Check the fuel filters?

If you have no smoke it would sound like a fuel problem a non wastegated turbo will need a fair bit of fuel being burnt and engine load to get it on song , could be a govener problem , rack sticking , the throttle linkage isn't giving full idle at the pump or a filter/supply is part blocked or transfer pump isn't giving enough pressure ...

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Mon, May 30, 2016 5:14 AM

lil cat mec

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Reply to cheshire cat:

If you have no smoke it would sound like a fuel problem a non wastegated turbo will need a fair bit of fuel being burnt and engine load to get it on song , could be a govener problem , rack sticking , the throttle linkage isn't giving full idle at the pump or a filter/supply is part blocked or transfer pump isn't giving enough pressure ...

Sounds like a fuel issue, air restriction would cause excessive smoke. What's fuel pressure under load? Check for full throttle travel, you can move the lever to full throttle then go to the pump and see if you can turn it and weather it increases rpms or not.

cheers

1935 CAT 22 2f4455W
CAT 951

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Mon, May 30, 2016 5:44 AM

edb

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Reply to lil cat mec:

Sounds like a fuel issue, air restriction would cause excessive smoke. What's fuel pressure under load? Check for full throttle travel, you can move the lever to full throttle then go to the pump and see if you can turn it and weather it increases rpms or not.

cheers

Hi cab,
boost for 36A with 2M5488 turbo should be around 29 Inches of Mercury at Full Load engine speed of 1200 Rpm's.

Correct Serial Number, as always, gets correct Data as there is a few "Hg difference but around 28 to 29 "Hg would be fine.

29 "Hg = around 14 psi.

Good trouble shooting info given by others above as a starting point--check the basic things first.
Cheers,
Eddie B.

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Mon, May 30, 2016 7:40 AM

neil

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Reply to edb:

Hi cab,
boost for 36A with 2M5488 turbo should be around 29 Inches of Mercury at Full Load engine speed of 1200 Rpm's.

Correct Serial Number, as always, gets correct Data as there is a few "Hg difference but around 28 to 29 "Hg would be fine.

29 "Hg = around 14 psi.

Good trouble shooting info given by others above as a starting point--check the basic things first.
Cheers,
Eddie B.

36A is not a "whistler" so the noise won't say much. Check the throttle is opening right up - give it a good yank back hard

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Mon, May 30, 2016 10:55 AM

cab

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Reply to neil:

36A is not a "whistler" so the noise won't say much. Check the throttle is opening right up - give it a good yank back hard

Air filter and all other filters are new. Fuel pressure good. Aren't we ignoring that there is no boost?

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Mon, May 30, 2016 12:11 PM

lil cat mec

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Reply to cab:

Air filter and all other filters are new. Fuel pressure good. Aren't we ignoring that there is no boost?

low fuel supply will cause no boost, boost pressure is set by the excessive exhaust pressure and restricted intake due to valves being closed.. unless your intake manifold gasket is leaking and or intake tube leaking a lot of air there should be no issues.. assuming the turbo spins as it should.

1935 CAT 22 2f4455W
CAT 951

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Mon, May 30, 2016 12:20 PM

catsilver

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Reply to lil cat mec:

low fuel supply will cause no boost, boost pressure is set by the excessive exhaust pressure and restricted intake due to valves being closed.. unless your intake manifold gasket is leaking and or intake tube leaking a lot of air there should be no issues.. assuming the turbo spins as it should.

Could be the diaphragm ruptured in the fuel/air ratio control.

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Mon, May 30, 2016 1:41 PM

cheshire cat

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Reply to cab:

Air filter and all other filters are new. Fuel pressure good. Aren't we ignoring that there is no boost?

No as others said thats the symptom not the cause !!!! you have enough air to burn the fuel it's getting so no smoke , look at the older tractors when you gun them from idle you get a puff of black smoke then the turbo spools
up and they run clean , you have some pump , rack, or linkage issue if you are sure the injection pump is getting plenty of fuel ...

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Mon, May 30, 2016 1:44 PM

mrsmackpaul

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Reply to cheshire cat:

No as others said thats the symptom not the cause !!!! you have enough air to burn the fuel it's getting so no smoke , look at the older tractors when you gun them from idle you get a puff of black smoke then the turbo spools
up and they run clean , you have some pump , rack, or linkage issue if you are sure the injection pump is getting plenty of fuel ...

my non expert thoughts for what they are worth

you have two ways to tackle this start from the turbo and work back or start from the air and fuel side and work forward

does the fuel pressure gauge return to zero or low when the motor is not running as in is the gauge working fully as to be expected ??
can you screw a second gauge on quickly some were just compare
Because as has already been said it sounds like its not getting the fuel to create the power to make the exhaust spin the turbo quick enough to make the boost

It may well be a turbo issue but if it was I would expect to see plenty of black smoke as the fuel was getting poured in but not enough air to make it burn properly

I was once told "Paul if you have no smoke you arent getting fuel to burn" and thats proven to be pretty spot on

Another fella told me years ago "Paul always fix the obvious first" that also works most of the time

Another bloke taught me "dont spend any money to you prove its the problem other wise your just guessing"

and theres more but I wont bore you but using these three simple rules sort of tells me were I would start

Paul

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Mon, May 30, 2016 4:28 PM

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