Lower power

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Lower power

January 13, 2021, 07:42:01 pm

The coach doesn't seem to pull as hard this winter from last. What is the expected turbo boost. I'm getting 24 lbs. boost.

Re: Lower power

Reply #1 – January 13, 2021, 08:09:41 pm

Quote from: oldguy – January 13, 2021, 07:42:01 pm

The coach doesn't seem to pull as hard this winter from last. What is the expected turbo boost. I'm getting 24 lbs. boost.

CAT, Cummins or Detroit, 24 lbs should do you well for power. I think we get about that at sea level. You have a waste gate turbo so should get about the same boost at altitude. If you are getting 24 lbs, it can't be a restricted fuel filter. Check air cleaner gauge.

Lower tire pressure now? Might check for an intercooler (CAC) crack or leak.

Pierce

Re: Lower power

Reply #2 – January 13, 2021, 08:31:21 pm

Think I was making 28-29 lbs of boost as I recall. Plan to take it out tomorrow I'll double check.
Scott

Re: Lower power

Reply #3 – January 13, 2021, 10:30:54 pm

Scott I think I was getting that also. Let me know for sure and then I will see what's causing it. Pierce don't want it to be the CAC
I had one rebuilt on my Dynasty. Fuel filters would be the best or and air filter.

Re: Lower power

Reply #4 – January 14, 2021, 12:35:26 am

Usually, a filter that is starting to clog will show up first by limiting the fuel and power the engine produces. This in turn reduces the exhaust flow through the turbo and limits the boost. This typically shows up on grades or going up an on ramp.

By looking at the air cleaner restriction gauge, you can tell the condition as the reading is a tell tale type with the maximum restriction remaining on the little gauge until it's reset. Driving in wet winter weather can dampen the air cleaner element so it restricts enough to cause power and boost loss. It can also result in higher EGTs especially in mechanical engines.

Pierce

Re: Lower power

Reply #5 – January 14, 2021, 01:11:37 am

Donaldson fuel minder fuel filter restriction gauge. Shows filter restriction.
Racor RK32037 FILTER SERVICE INDICATOR-1/8"
Scott

Re: Lower power

Reply #6 – January 14, 2021, 07:51:44 pm

OAT about 70 deg 29 lbs

Re: Lower power

Reply #7 – January 15, 2021, 08:05:16 pm

Thanks Scott I thought I had seen it up there before. On the way back to day it went about 25 lbs when engine was cold and after
engine got hot it was lower. I will check it out tomorrow and it won't hurt to change fuel filters. I might put a fuel gauge in to see
what the fuel pressure is. It would be nice if there was one that could be set up on the Silver leaf.

Re: Lower power

Reply #8 – January 15, 2021, 10:07:05 pm

Quote from: oldguy – January 15, 2021, 08:05:16 pm

Thanks Scott I thought I had seen it up there before. On the way back to day it went about 25 lbs when engine was cold and after
engine got hot it was lower. I will check it out tomorrow and it won't hurt to change fuel filters. I might put a fuel gauge in to see
what the fuel pressure is. It would be nice if there was one that could be set up on the Silver leaf.

I put a gauge after our secondary filter but unless you can send the reading to your dash, it does not do much good as you need the PSI at full throttle at max load. Any restriction in the filters won't show up at light or medium throttle.

There are extra wires back there that go to the front so a sensor at the engine and the gauge up front.

Our Pro-Link will read the fuel temperature but not the pressure from the DDEC II.

Pierce

Re: Lower power

Reply #9 – January 16, 2021, 10:23:02 am

There was a post on this site that talked about how the air filter minder had gone bad and was still showing the filter good. My suggestion is to change the air filter first. At least you then know that is not the problem. If still a problem look at the CAC to see if it has a crack in it that is causing the boost to escape before being pushed in the engine.

Re: Lower power

Reply #10 – January 16, 2021, 10:26:30 am

Air filter minders are EASY to check:

Remove the hose that goes to the filter minder (the pipe between the filter to turbo) and suck on it. That should peg it in the red and stay there until you reset it. Push the reset button.

Only other issue (and I have never seen it) is if the port the hose attached to on the pipe is clogged. That would probably indicate some other significant issues, as that is on the "filtered" side of the air filter.

Re: Lower power

Reply #11 – January 16, 2021, 10:28:16 am

How old is the air filter and do you have a Donaldson pre-filter water trap before the air filter,the ones that do not seem to be the ones that get the wet filter.

Re: Lower power

Reply #12 – January 16, 2021, 12:59:35 pm

Quote from: wolfe10 – January 16, 2021, 10:26:30 am

Air filter minders are EASY to check:

Remove the hose that goes to the filter minder (the pipe between the filter to turbo) and suck on it. That should peg it in the red and stay there until you reset it. Push the reset button.

Only other issue (and I have never seen it) is if the port the hose attached to on the pipe is clogged. That would probably indicate some other significant issues, as that is on the "filtered" side of the air filter.

So the 1/8 hose to 1/8 NPT fitting on the air filter housing has a slintered bronze filter in it. They are very fine and quite subject to clogging up. I am guessing it is to protect engine in case of a sense hose failure? Mine was almost plugged. Cleaned with brake cleaner after removed. So check both directions, to filter minder then to filter housing.
Scott

Re: Lower power

Reply #13 – January 16, 2021, 01:09:44 pm

Quote from: John44 – January 16, 2021, 10:28:16 am

How old is the air filter and do you have a Donaldson pre-filter water trap before the air filter,the ones that do not seem to be the ones that get the wet filter.

I noticed yesterday that the evacuator valve on my Donaldson precleaner is very active at idle. It is constantly puffing out air then closing, was quite surprised to see this much operation. I would think it would closed at higher power settings do to increased flow but don't know. I can't express enough how much I like Precleaners. The last six installations have sold me on what a difference they make. I plan to rig up a trap can or bag at the exhaust/vacuator valve to see what is removed.

Re: Lower power

Reply #14 – January 16, 2021, 01:25:38 pm

It's the air filter that's the problem and a pre-filter is next. Anybody have a part number for the pre-filter for the M11.
This filter isn't very old and has 8,000 miles on it.

Re: Lower power

Reply #15 – January 18, 2021, 10:08:39 am

The air filter has made a difference and I will change the fuel filters next weekend and see if that will also make a difference.
I like doing one thing at a time and then I will know for sure what the problem was.

Re: Lower power

Reply #16 – January 18, 2021, 10:37:21 am

Quote from: oldguy – January 16, 2021, 01:25:38 pm

It's the air filter that's the problem and a pre-filter is next. Anybody have a part number for the pre-filter for the M11.
This filter isn't very old and has 8,000 miles on it.

Pre-filter? Where is that?

Re: Lower power

Reply #17 – January 18, 2021, 11:02:24 am

If you have one it's in line before the air filter.

Re: Lower power

Reply #18 – January 18, 2021, 11:07:37 am

Quote from: John44 – January 18, 2021, 11:02:24 am

If you have one it's in line before the air filter.

Is that in the same "box" as the air filter, inside the tubing leading to the filter box, or a separate housing? I have not noticed anyplace obvious. Is this a stock configuration?

Thanks!

Re: Lower power

Reply #19 – January 18, 2021, 11:13:16 am

Quote from: oldmattb – January 18, 2021, 11:07:37 am

Is that in the same "box" as the air filter, inside the tubing leading to the filter box, or a separate housing? I have not noticed anyplace obvious. Is this a stock configuration?

Thanks!

Replay 13 shows picture. I installed in down pipe prior to air filter on my U320. Heard some may have factory installation , I don't know, I do know they work well.
Scott
Donaldson Precleaner

Re: Lower power

Reply #20 – January 18, 2021, 04:14:50 pm

Quote from: oldguy – January 18, 2021, 10:08:39 am

The air filter has made a difference and I will change the fuel filters next weekend and see if that will also make a difference.
I like doing one thing at a time and then I will know for sure what the problem was.

Did you notice an increase in boost after changing air filter?

Re: Lower power

Reply #21 – January 29, 2021, 09:13:54 am

I changed the fuel filters, cut the primary filter apart and it was fine so no difference in power. Last night I went to start the engine
and it wouldn't start. Went out and pushed the air purge button and the engine started immediately. One other time the engine
was hard starting, like there was air in the system. When I get home today I will change the fuel line between the pump and the
primary filter.

Re: Lower power

Reply #22 – January 29, 2021, 09:24:20 am

Quote from: oldguy – January 29, 2021, 09:13:54 am

...air in the system. When I get home today I will change the fuel line between the pump and the primary filter.

If that doesn't help, next logical step is replace fuel line between fuel tank and first filter.

"Air in the system" is classic symptom of failing fuel lines. Based on my reading here. No personal experience....yet. Our fuel lines still OEM, and seem to work fine. Knock wood.

Re: Lower power

Reply #23 – January 29, 2021, 09:45:37 am

Quote from: oldguy – January 29, 2021, 09:13:54 am

Went out and pushed the air purge button and the engine started immediately. One other time the engine
was hard starting, like there was air in the system.

If your coach has the Racor style primary filter with the clear plastic bowl, you might check the bowl for cracks and replace the four o-rings. I have not experienced it, but others have reported air leaks at those locations.

Re: Lower power

Reply #24 – January 29, 2021, 10:20:56 am

The Racor has 4 - 6 O rings, any one of which can leak and lead to poor running or no start.

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