5.9 temp and oil psi

Hazin · 08-25-2018, 08:29 PM

Took the bus cross country and was getting 55mph at 1700 with oil and temp sitting dead center. After a ton of reading got the tst power kit and replaced the fuel plate under the afc hoping to gain a few mph.

After install doing 60mph at 1700 however oil pressure running little over 65 (probably ok), and temp creeping past 210 which is a bit of a increase.

Anyone familiar with this and have a suggestion other then putting stock plate back in, woukd really like to cruise a bit faster but not up for damaging the bus. Seems I read a dozen places where people did this without issue.

Mr4btTahoe · 08-25-2018, 08:48 PM

Quote:

Originally Posted by Hazin

Took the bus cross country and was getting 55mph at 1700 with oil and temp sitting dead center. After a ton of reading got the tst power kit and replaced the fuel plate under the afc hoping to gain a few mph.

After install doing 60mph at 1700 however oil pressure running little over 65 (probably ok), and temp creeping past 210 which is a bit of a increase.

Anyone familiar with this and have a suggestion other then putting stock plate back in, woukd really like to cruise a bit faster but not up for damaging the bus. Seems I read a dozen places where people did this without issue.

Have a pyrometer? I'm curious what EGTs are running. What was your typical temperature before the mods?

Oil pressure is fine... and honestly, 210F isn't anything to worry about... but if it was a substantial jump in what it used to run, I'd look into it. More then likely, EGTs are a good bit higher. Need to know what exhaust temp is running.

o1marc · 08-25-2018, 09:03 PM

180-190 is normal operating temps, 210 is not critical and I wouldn't worry about damaging anything unless it was sustained at better than 230. Even my bus will see 230 temps on hills if you stay in it.

Hazin · 08-25-2018, 10:14 PM

50 and 180 seemed to be the normal on a 12 hour trip before. On a 30 minute trip now is 65 and 210.

I'll have to look into the other

magnakansas · 08-25-2018, 10:31 PM

so the water temp gauge is showing higher temperatures and the oil pressure is higher too.

I would expect with a higher water temp, and the same engine rpm, the oil pressure would be lower.

cadillackid · 08-26-2018, 08:43 AM

check your grounding for the gauges.. if the ground is bad, its possible that the oil PSI gauge is obtaining its reading with grounding through the temp sensor ..

I didnt see what transmission this has.. but if its an AT545 then the engine might run higher RPM against the converter stall thus creating a higher oil PSI.. (and a HOT transmission!).
-Christopher

Gdog 5651 · 08-26-2018, 11:37 AM

It seems to me that 1700 rpm is substantially under red line and if so should not be causing a temp problem.My 5.9 runs a 2200 rpm all day long and even with a AT545 does not build engine heat and to avoid trans temp problems I built and installed a MONSTER trans cooler.

Gdog 5651 · 08-26-2018, 11:42 AM

And after installing the pump plate it is likely over fueling somewhat causing higher EGT after modifying fuel system a pyrometer is always a good idea if not near mandatory.

Free Bird · 10-29-2018, 12:29 AM

Hi GD, I have a 36 pas 93 ford with 5.9 and 545. Seems I'm runin around 2200 rpm at 60, when I tie into a hill the rpm goes up and the speedo goes down. I'm told this is normal for the 545, I'm thinkin with your bigger bus this must be a bigger issue. What are your thoughts on improving fuel mileage?

Ronnie · 10-29-2018, 06:56 AM

Anytime you change from the factory fuel setting you really must have an exhaust temp gauge. High egt's make for melted pistons.

1700 rpm's seems over geared for it. 2200-2300 is a nice cruising rpm for the 5.9. Do you know what your gear ratios are? and do you know what speed 2200rpm's would be if you had the power to get there?

Hazin · 10-29-2018, 08:16 AM

It won't go over 1700 rpms, guessing govenor springs as well as horrible gear ratio. Gears or bigger rear tires are high on my list of to do

So installed a pyrometer and did another 2 20 hour trips. 1700 rpm, 57mph, no issues other then being slow.

Original voltage gauge went out on the trip so guessing my original Gauges do have a ground issue or just going out as someone suggested.

I tend on installing boost guage, as well as replacing original guages with new soon.

Gdog 5651 · 10-29-2018, 10:41 AM

Quote:

Originally Posted by Free Bird

Hi GD, I have a 36 pas 93 ford with 5.9 and 545. Seems I'm runin around 2200 rpm at 60, when I tie into a hill the rpm goes up and the speedo goes down. I'm told this is normal for the 545, I'm thinkin with your bigger bus this must be a bigger issue. What are your thoughts on improving fuel mileage?

I think usually in terms of increasing power with a 5.9 in a bus as they are a little underpowered in most bus applications but what is reversed over gas engines is what increases power in diesel (within reason) seems to also help fuel economy. I did the fuel plate gov spring and revamped the air cleaner in mine but also did the prevent things killer pin prevent amsoil in motor transyn in the 545 monster trans cooler and keeping the tires pressured correctly those items don't make it a KTA450 but it is comfortable to drive and it is not the largest skoolie made but it is pretty big and is powered by one of smaller power combinations also if you are wondering it is doing about 8.5 mpg I run it @2250rpm most of it's life.I just retired a 1976 Sportking type C 16ft on a dodge chassis that never saw 6 mpg in its life and was 1/3 the size! Gene

Gdog 5651 · 10-29-2018, 10:54 AM

1700 RPM is nowhere near governered rpm before you start throwing money at your problem save yourself some money and some aggravation by spending some money and time at a competent repair facility find out why the engine isn't reaching governered speed I assure that at maximum regulated rpm the economy (should) improve and driveability also. Gene

cadillackid · 10-29-2018, 10:57 AM

in a lot of cases school bus engines are highly de-rated compared to their truck and consumer-based counter-parts..

if you stay within the factory constraints of fueling and power-adding then you are generally safe from melted pistons and the like.. what I mean by that is not turning it up beyond what was offered by the factory with your set of hardware... with mechanical engines its easy to slide fuel plates and advance timing to snag a few extra ponies.. most of these engines were often the same long block and even same turbo, etc but were just "turned down" for the sake of a school bus.. if you have a 170 HP engine but the factory offered it as a 200 HP engine then its pretty safe to turn it up and match the specs for the 200 HP variant.. now if the factory also offered 250 HP but had a different turbo or headgasket etc.. then thats where you want to be sure to have a pyro gauge, monitor for rod stretch, valve float etc.. because you would be going beyond your hardware set.

adding power to a smaller engine im convinced helps with MPG as long as you dont go overboard.. an underpowered engine likely results in you running it floored, often downshifting and turning high revs taking the engine out of its "sweet spot" just to keep it moving.. a little more power and you can use that higher gear and gear it in for its sweet spot..

installing too large displacement engine can result in lower MPG;s as you are then compressing air in cylinders expending energy when there is not much need for it.. (well over-powered).. so its important to match engine / drivetrain to your expected load, driving style, expected terrain
-Christopher

Ronnie · 10-29-2018, 05:25 PM

Just out of curiousity does it go over 1700rpms in any gear, or in neutral if you floor it?

Hazin · 03-16-2019, 05:11 PM

ive never tried in neutral, good idea

Hazin · 03-16-2019, 05:12 PM

ill try that when I fire it up later this month, good idea

Hazin · 03-16-2019, 05:12 PM

Quote:

Originally Posted by Gdog 5651

1700 RPM is nowhere near governered rpm before you start throwing money at your problem save yourself some money and some aggravation by spending some money and time at a competent repair facility find out why the engine isn't reaching governered speed I assure that at maximum regulated rpm the economy (should) improve and driveability also. Gene

It had a full check up and service at cummins, they found no issues, did a annual service and said its not goverened at all. They recommended buying a beefed up fuel pump or sending mine in to bosch and have it changed.

they also recommended replacing the rear end gears to get more speed.

Ronnie · 03-16-2019, 06:11 PM

Until you get the rpms up I would not change gears. 1700 rpms max is not right. So need to get that corrected first. I would still run it in neutral to see what it max out to. I would also check throttle linkage with the engine off. Have someone hold it on the floor and look to see if it does move it at the injection pump to full throttle.

WARGEAR · 03-26-2019, 07:33 AM

I didn’t see it mentioned here yet so I’ll add in this. Maybe your Tachometer isn’t reading correctly. Maybe you are running at max RPMs but only see it rev to 1700. It’s been said your gauges could be failing and I’ve seen Tachs and Speedos do some crazy stuff too. Just a thought!

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