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Bogging down in East Texas
O K here I go for the first time…
My series 60 ’98 has been fabulous…no issues and is serviced regurlarly….I drive it with kid gloves…
On our recent trip of the past few days, the bus began to “bog” down as if the fuel filter was clogged…. the bus when under any “uphill incline” would not generate “power”…. the turbo would only hit as high as 15 pounds…. as the bus slowed, guess what….it downshifted which of course caused the engine to uptick in revenues which further starved the fuel and it would continue to slow down to perhaps 30 MPH…. it would then upshift and the revs would go back down (1300) and the bus began to gain speed up to about 60 MPH but stayed there if there was any incline at all…
All other functions of oil pressure, temperature of engine and tranny excellent…
The ambient temperature was over 100 degrees …probably 110 on the highway…
I called Stewart and Stevenson (Detroit Diesel) and they suggested any number of things. I first changed the fuel filter and it was better for a brief period of time… 15 miles or so… At that point, it did register 22 pounds on the turbo until it started bogging again….I had already checked all of the hoses and clamps on the turbo intake… all seemed to be good as far as I could tell…… I drove with great care and kept the revs down and took our time…
S & S has me on a standby to bring the coach in by appointment in 10 days or sooner…. great guys..
S & S said it could be anything from an injector, a fuel pump or even the turbo…. I do not think it is the turbo… it certainly did not heat up.? .. I think the low turbo pressure was from the fuel starved aspects of the engine… but what do I know..?.It would seem to me that the turbo can’t make power without the fuel…?
I must say, I was very appreciative of driving such an excellent machine…. we had the grandchildren with us and we were pulling our Nautique ski boat… about 250 miles…. got home safely which is most important….
Any thoughts on the bogging down????
Pres
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21 Replies
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You said “changed filter”. Does your coach have 1 or 2 fuel filters, a primary and secondary. It does sound like a fuel delivery problem.
Ken
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Pres, was it bucking?
Fuel starvation is likely to act like you describe. Will you be able to hit and hold 2100 RPM in neutral? From a standstill is it slow to build speed and power?
If you replaced the primary filter did you cut it open? That would reveal if it was a fuel starvation issue as a result of clogged filters.
Did you see if the flex hoses from the turbo to the charge air cooler have a hole or crack in them? That will affect turbo boost. You would need a mirror to be able to see all around them.
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Pres,
Did this start after refueling?
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All great questions…. I only replaced one filter because that was the only one I knew of and did not want to get under the coach without proper protection just to find the second one…. I did not try the 2100 rpm test because I did not know to do so…. and I wll cut the old fuel filter open tomorrow…I did start having the problem before I refueled so I believe the fuel is good fuel…
Thank you for all of the questions… I will give answers tomorrow.
Pres
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Pres,
You will have at least two filters and if it is a dirty fuel problem the primary filter is the one that must be replaced first and the old one examined. If it is clean your problem is other than dirty fuel or clogged filters. If it is dirty as in the pleated filter is covered with dirt or algae that is your problem. That being the case your solution is to carry extra filters and change them at the first sign of a problem until such time as the fuel gets cleaned up. Fuel “polishing” might be required if you do have a tank of fuel that is contaminated.
The problem may have nothing to do with your last refueling if it is fuel related. The filters could be getting plugged over a longer period of time. If the coach has not been used frequently extended storage could allow the growth of algae which loves the high humidity you likely experienced during that rainy weather you had. Algae will plug filters.
If it is not your fuel filters that are the problem it could be a leak in the turbo system. Even a relatively small leak can reduce mainfold pressure sufficiently to cause the loss of power. A detailed inspection including the charge air cooler will reveal if that is the problem.
The two items listed above are the easy cheap ones to deal with and you can do them both yourself. If neither of them proves to be the problem then it gets more involved and S&S becomes the place to take the coach.
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Jon mentioned algae.
Especially in hot and humid climates, the slightest bit of algae can “bloom” quickly in to a big problem. If the coach had been sitting around for any period prior to this trip, algae could indeed be clogging your fuel filters. Your symptoms sure sound like it.
Since I mostly travel in the Southeast region, I routinely use Biobor JF with each fillup to prevent algae. It only took me one time to have the problem and months to correct it to realize that prevention is much better than correction. Even though I usually travel every week, filling up every week, I am always concerned with the potential to clog filters. Our coach is sitting at Jeff’s shop waiting on parts. I am very glad that my fuel tank is treated with Biobor JF. I have little concern about algae building up while the coach sits in hot and humid eastern TN weather.
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If your problem ends up fuel related, this is a great product you can get from Parliament:
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After church this morning I went to the warehouse to see if indeed I have two filters. Our coach is a ’98 model CC and a ’98 year chassis having been porduced in October – December of ’98. In looking at the engine, I believe it is a 1997 Series 60 engine itself…..I looked for the second fuel filter and there is not a second filter on the passenger side of the engine. If there is another fuel filter, I do not see it anywhere. On most, the primary filter is below the air compressor. I do not have one there and do not see another filter except the anti-freeze (1) at the rear and the transmission filters (2) on the drivers side. If anyone has an idea where it could be, I will go back and search but it would have to be on the driver’s side of the engine in front of the transmission filters. It is absolutely not evident on the passenger’s side. You can certainly be correct that I should have two filters..that would make sense.
Some of you gentlemen would have paid big money to see me trying to split the old filter open to investigate its contents. Nonetheless, I got it open and the membrane is a dark, dark green/blackened color similar to a dark oil and it would seem to me to be very hard for anything to go through the membrane because of its possible low permeability… but I do not know what the fuel pressure does to the flow. On first appearance, it also does not seem to have much of a porosity percentage….in clear words to me, it is as hard as slightly wet cardboard… When rubbing the oil moistened membrane material, some of which I removed, it is granularly smooth and nothing comes off against my fingers…in simpler words, I do not know if there is algae there or not. …If so, it is not evident to my untrained eye…and is not on my hands when handling the filter…
I thank everyone for their thoughts and concerns. I am becoming convinced tghat I have algae in the fuel…The product suggestions will be followed up on regardless of the problem I am currently enduring…
My mechanical experience has been historically relegated to building “mouse” and “rat” motors for our Chevy’s… I can only spell diesel…
I will continue to solve the problem by first having an in-house mechanic confirm whether or not I do or do not have two filters…..
Thanks again….
Pres
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Pres, Have I ever lied to you? I may have stretched it a little, but in this case I ain’t lying. You have two fuel filters. One is behind the chassis batteries, and a second is further aft about in line with the first. Some converters offered alternatives, usually something like a Racor with the large amber fuel bowl so you could see dirt or water. But regardless there are two filters if not more.
Can any of you CC guys confirm what CC did as far as fuel filters? Buddy? Anyone else with a similar vintage that can help Reagan?
What you describe sure sounds like algae and if the filter is not the primary you problem goes away with new fuel filters followed by a fuel polishing.
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I admit, I did not llook behind the batteries… I just got back…
I will go later this afternoon… I BELIEVE…. I BELIEVE… I hope I find iot today.
THANKS,
Pres
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Jon,
I believe I have the Racor set up…. I definitely do not have two fuel filters that look like what you wiould expect.
There is a Racor? in line….. I will work on that angle…
I am still taking it into Stewart & Stevenson as soon as there is an opening…
Best policy is to have them put the electronics on it and check the injectors and other parts that could be involved. I am leaving the 31st to go to South Bend to see Texas whip up on Notre Dame…
Pres
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Here are some pics of the 30 micron primary fuel filter(Racor 1000FG) with drop-in element, the seal kit, and the 10 micron secondary spin-on filter that is located on the engine next to the oil pan on curbside.
Here are some different brand part #s that will work:
For the drop-in element Racor 1000FG housing: a) Racor 2020PM-OR; b) Fleetgaurd FS20203; c) Baldwin PF7890-30.
Use Racor seal kit# RK 11-1404.For spin-on secondary: a) Fleetgaurd FF5206, b) Baldwin BF 5810; c) Wix 33120; d) Donaldson P556916; e) Fram P1147G
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Pres,
My 02 CC is on a 2000 shell and is almost identical to Don’s photos. The Racor is mounted just slightly different and like Don my coach has the Racor and 1 spin on filter. I have the Prevost Maintenence Manual and it shows the filter/ separator as an upgrade to the standard Primary spin on filter. This should be aft of the spin on you cut apart. I wouldn’t discount the possibility that 2 spin on filters exit with the Racor but the Prevost manual reads as described. -
Got it… now I know what it looks like and it is there!
I was looking for the more standard appearing filter…
I will work on it today assoon as can get to it….and thank each of you so very much…
Pres
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Pres,
If the Racor is primary when you pull out the filter cartridge you may see if coated with a “sludge”. If so that is the problem. Usually the debris finds its way into the bottom bowl. The bowl is removeable if it is loaded with crud. It is an excellent visual check on the general condition of the fuel and will show water or dirt.
The internal filter element should be about 30 micron if it is primary, 10 micron if secondary. I don’t know how CC set it up. O rings and gaskets come with the new element, but not for the bottom bowl. You can reuse it if careful or get a new one if the bowl is taken off.
Here’s a tip every one of has found out the hard way. The Racor will be filled with fuel ordinarily. When you remove or replace the fuel filter from a fuel filled housing there is some resistance to pulling it up and out, or when pushing it back down in place. Be very careful either way. When the rubber seal at the top of the filter gets to the transition point where the pressure required to push it down in place or pull it up from the housing releases you are going to get splashed with diesel fuel. If you expect the drag to diminish and anticipate it you might not slop fuel all over you and the coach. Ask us how we know stuff like this.
Any time you change fuel filters fill them with fuel.
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