no boost

cab

Topic Author

Offline

Send a private message to cab

Posts: 388

Thank you received: 0

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!

Please log in or create an account to join the conversation.

Mon, May 30, 2016 3:25 AM

Rome K/G

Offline

Send a private message to Rome K/G

Posts: 6,092

Thank you received: 0

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?

Please log in or create an account to join the conversation.

Mon, May 30, 2016 4:53 AM

cheshire cat

Offline

Member

Send a private message to cheshire cat

Posts: 195

Thank you received: 0

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 ...

Please log in or create an account to join the conversation.

Mon, May 30, 2016 5:14 AM

lil cat mec

Offline

Send a private message to lil cat mec

Posts: 526

Thank you received: 0

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

1990 CAT D6H 4GG04120

2012 CAT 272C RED02823

1971? CAT 951B 86J01212

Please log in or create an account to join the conversation.

Mon, May 30, 2016 5:44 AM

edb

Offline

Member

Send a private message to edb

Posts: 4,168

Thank you received: 60

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.

Please log in or create an account to join the conversation.

Mon, May 30, 2016 7:40 AM

neil

Offline

Member

Moderator

Admin

Super Admin

Send a private message to neil

Posts: 7,329

Thank you received: 66

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

Please log in or create an account to join the conversation.

Mon, May 30, 2016 10:55 AM

cab

Topic Author

Offline

Send a private message to cab

Posts: 388

Thank you received: 0

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?

Please log in or create an account to join the conversation.

Mon, May 30, 2016 12:11 PM

lil cat mec

Offline

Send a private message to lil cat mec

Posts: 526

Thank you received: 0

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

1990 CAT D6H 4GG04120

2012 CAT 272C RED02823

1971? CAT 951B 86J01212

Please log in or create an account to join the conversation.

Mon, May 30, 2016 12:20 PM

catsilver

Offline

Send a private message to catsilver

Posts: 1,644

Thank you received: 0

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.

Please log in or create an account to join the conversation.

Mon, May 30, 2016 1:41 PM

cheshire cat

Offline

Member

Send a private message to cheshire cat

Posts: 195

Thank you received: 0

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 ...

Please log in or create an account to join the conversation.

Mon, May 30, 2016 1:44 PM

mrsmackpaul

Offline

Send a private message to mrsmackpaul

Posts: 1,456

Thank you received: 0

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

Please log in or create an account to join the conversation.

Mon, May 30, 2016 4:28 PM

Follow Us on Social Media

Upcoming Events

Testimonials