1994 U-280 Grand Villa overheating and fan speed issues 8.3

Topic: 1994 U-280 Grand Villa overheating and fan speed issues 8.3 (Read 576 times) previous topic - next topic

1994 U-280 Grand Villa overheating and fan speed issues 8.3

August 29, 2024, 12:20:09 pm

I have been fighting overheating for years in the summer. Here are pictures of how the hydraulic lines are hooked up. I have talked to FT and they have no record (building burned) of how the lines were actually hooked up. My fans do ramp up to high speed but are running at only about half of what they are supposed to run. They are turning (on high speed) about 860 RPM at about 1700 engine RPM Here are pictures and a diagram of what I have...Any help would be appreciated. The FT schematic is not much help.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #1 – August 29, 2024, 01:34:32 pm

Are the filters and oil up to specs? Maybe someone with the same setup can help.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #2 – August 29, 2024, 01:38:24 pm

Quote from: John44 – August 29, 2024, 01:34:32 pm

Are the filters and oil up to specs? Maybe someone with the same setup can help.

I got new filters from FT and change the oil

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #3 – August 29, 2024, 02:17:50 pm

Try taking some temp readings with a heat gun of before and after of the radiator and CAC,should have some difference,are you
sure both of them are really clean.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #4 – August 29, 2024, 02:40:53 pm

They are clean. I know that the fans are not running fast enough in high speed. I used a photo tachometer at about 1750 engine RPM and the fans were only turning about 860. I am reading that U-280 with dual fans, the fans should be 1928 rpm with an engine RPM of 1600. I am trying to wrap my head around why. I want to check the location of the hoses to make sure that they are correct. I know the solenoid is opening and closing as I am getting lower speeds before the engine reaches temp. The fans are running less than 1/2 as fast as they should according to this.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #5 – August 29, 2024, 03:13:49 pm

The pump and fan motors are wearing parts. Do you have ports and gauges to test pump pressure? Next would be delivery volume. You may have bad pump or relief valve. Only with gauges can you do a diagnosis without just throwing parts at it.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #6 – August 29, 2024, 03:19:57 pm

I was just shopping for a gauge....My bet is the relief valve is bad.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #7 – August 29, 2024, 03:30:32 pm

Quote from: Karl Shurtleff – August 29, 2024, 03:19:57 pm

I was just shopping for a gauge....My bet is the relief valve is bad.

FT has the relief valve 52 bucks... I think that I will try that....cheaper than a gauge.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #8 – August 29, 2024, 03:35:10 pm

Karl,

Over the years, I have seen several Forum posts describing the hydraulic fan hose setup that you describe. Our '93 U280, however, does not have that same hose configuration. On our coach, the output hose from the hydraulic pump goes directly to one of the fan motors. There is a hose connecting the two fan motors. From the second fan motor a return hose goes back to the tank. That's it - there is no electric solenoid valve on our coach. The RPM of our fans varies directly with engine RPM. We have never had any problem with the engine over-heating, and we have driven in some really hot temperatures. I don't know if our coach was modified from the factory original configuration by a previous owner, or if it was built this way.

I rebuilt our hydraulic pump not long after we purchased our coach. I did this mostly as a preventative maintenance project, and to address some problems with the pump drive belt. Rebuilding the pump did not make any noticeable difference in engine cooling performance.

Vickers V10 Hydraulic Pump Rebuild

Can you tell if your hydraulic pump is original? Could it have been replaced at some point with an incorrect pump model?

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #9 – August 29, 2024, 04:09:14 pm

Quote from: Chuck & Jeannie – August 29, 2024, 03:35:10 pm

Karl,

Over the years, I have seen several Forum posts describing the hydraulic fan hose setup that you describe. Our '93 U280, however, does not have that same hose configuration. On our coach, the output hose from the hydraulic pump goes directly to one of the fan motors. There is a hose connecting the two fan motors. From the second fan motor a return hose goes back to the pump. That's it - there is no electric solenoid valve on our coach. The RPM of our fans varies directly with engine RPM. We have never had any problem with the engine over-heating, and we have driven in some really hot temperatures. I don't know if our coach was modified from the factory original configuration by a previous owner, or if it was built this way.

I rebuilt our hydraulic pump not long after we purchased our coach. I did this mostly as a preventative maintenance project, and to address some problems with the pump drive belt. Rebuilding the pump did not make any noticeable difference in engine cooling performance.

Vickers V10 Hydraulic Pump Rebuild

Can you tell if your hydraulic pump is original? Could it have been replaced at some point with an incorrect pump model?

I was just reading your post on your V10. I am sure it is original, It was my fathers coach and it only had 23K miles on it when he passed. I started chasing this problem several years ago. I took it to Keith over the winter to have him fix it and we thought that he did. Of course I took it to him during an ice storm so it was hard to tell if it was overheating. It does fine in the cold weather, but in the Texas summers it get hot. I just found the post today that had the fan RPM's and confirmed that they are running too slow. My guess is it is the check valve in the picture. I am running to NAC in the morning to pick it up. If that does not do it I will get a gauge and start checking pressures. The Hydraforce valve is definitely opening since the fans ramp up...just not enough. Fingers crossed.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #10 – August 29, 2024, 04:47:49 pm

Maybe change the drive system to speed up the pump ?

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #11 – August 29, 2024, 05:34:22 pm

Unplug the electrical connection at the valve and see if they get faster. The valve should default to closed without power and should send all flow from the pump to the motors.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #12 – August 29, 2024, 05:57:24 pm

I have removed the power and confirmed that the fans ramp up to high speed. Although higher than the slow speed, they are not even close to the correct high speed. They ramp up to about 860 rpm from 216 rpm. That is why I am thinking the relief valve is bad.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #13 – August 29, 2024, 06:46:09 pm

If there is relief valve. It may have bleed off line . Maybe plug this bypass line to verify that the valve closes?

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #14 – August 29, 2024, 07:10:09 pm

Karl and I have the same issue, here are pictures of my system. Hope this helps. I could not post more pictures, this is the relief value.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #15 – August 29, 2024, 07:25:23 pm

Knowing nothing of your system the electric bypass valve if internally bypassing it will get hot and be noisy by the function of bypassing oil thru it. The other thing that came to mind was a hard pump drive belt slipping. Since you have the rpm indication could you compare pulley speed to belt speed?

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #16 – August 29, 2024, 07:28:44 pm

Karl,
Twig was working on build #4490 last year. We have the same system. If you search for "94 U280 Hydraulic Fans" I had posted some info on it. I haven't tested mine yet. But it has what I believe is the correct pressure and fan speeds. I'm planning on check mine before I have a problem.
Mark C.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #17 – August 29, 2024, 07:30:39 pm

The valve may have slight scratch on the seat

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #18 – August 29, 2024, 10:21:45 pm

Quote from: pthurman48 – August 29, 2024, 07:10:09 pm

Karl and I have the same issue, here are pictures of my system. Hope this helps. I could not post more pictures, this is the relief value.

Pat,

That sure looks like a PSI adjustable valve. Don't see any electrical connection.

The screw and lock not (facing rear of coach) are likely adjustable.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #19 – August 30, 2024, 05:25:54 am

Like dsd said. The system has a fixed displacement pump. If it's pumping oil, it has to be going somewhere. you might be able to hear or feel the flow through the lines in and out of the relief valve or the control valve. The should also get hot from the pressure drop. Might help you figure out where the oil is going that's not making it to the fan motors. If you can get the numbers off the pump and motors that show displacement, you can check the numbers and see how much flow and speed you should be getting as well. You can also bypass the relief valve and control valve for testing to see if the fans get faster without them in the circuit.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #20 – August 30, 2024, 09:29:22 am

Quote from: wolfe10 – August 29, 2024, 10:21:45 pm

Pat,

That sure looks like a PSI adjustable valve. Don't see any electrical connection.

The screw and lock not (facing rear of coach) are likely adjustable.

FWIW, our U240 had the adjustable valve on the right frame rail just like Pat's pic. The high/low electric valve was on the left frame rail like Karl's pic in his original post.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #21 – August 30, 2024, 09:46:27 am

Again, not ASSUMING that the valve in Post #14 is the same as on our 1993 U240, but if it is, screwing the end screw (allen if I recall) one turn raised hydraulic PSI from 900 to 1500 PSI.

May be worth a short experiment.

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #22 – August 30, 2024, 11:43:28 am

Quote from: wolfe10 – August 30, 2024, 09:46:27 am

Again, not ASSUMING that the valve in Post #14 is the same as on our 1993 U240, but if it is, screwing the end screw (allen if I recall) one turn raised hydraulic PSI from 900 to 1500 PSI.

May be worth a short experiment.

Also remember that the relief springs have been under tension for years and are very active during operation. They will relax and are subject to fatigue and breakage. Goal is for the fan not to overspend at hi RPM, yes that's not your problem. If it bottoms out then you get the speed increase, you have a broken spring. Should be able to float during operation above certain speeds

Re: 1994 U-280 Grand Villa overheating and fan speed issues 8.3

Reply #23 – August 30, 2024, 07:54:49 pm

Yes Brett, I was just showing Karl the other component in our systems. It is an adjustable pressure relief valve for over pressure problems. I have replaced and adjusted mine with no change in fan speed.

Yes Dave you are correct. Mine is also just like Karl's

I am very interested in this thread. I have the same system with the same problem. I have posted many time about it. My fans run about 600RPM slow. I have replaced the pump, fan motors, high/low valve, adjustable relief valve and still my fans run slow. I have not replaced the check valve Karl is speaking of.

Foretravel Specs: CAT 3116
Pump Output 1600PSI @ 2750RPM
Fan Speed High 2930RPM @ 2750RPM
Fan Speed Low 1900RPM @ 2750RPM

Affiliate Notice