Bern and Sean Ford 5000

[johnofnewhaven]

Good afternoon. I'm having a problem with my 1974 Ford 5000 diesel. This is the one that I put a new head gasket on and repainted. Here's my problem. It is overheating. Now to eliminate the head gasket being the wrong one or on the wrong way I know for a fact that's not it. I also had the old radiator redone. It has all new radiator hoses and a new thermostat. This is actually the second thermostat that I put in it since I redid the head because I thought maybe the first one I got was crap but both thermostats I tested and they are opening correctly. The top radiator hose gets hot the top of the radiator gets hot but the bottom radiator stays cool and the bottom of the radiator stays cool. I am now thinking the water pump is bad. There is a slight wobble in the fan but it's only maybe 1/8 of an inch to 3/16 of an inch wobble. What are your thoughts? Before I order a new water pump and tear apart the front of the tractor again I would like your opinions. Thank you in advance.

 

[Bern]

You say ''it is overheating''. How do you know? Does the gauge simply read high or is it puking water out the overflow? If it's the gauge reading high, and your fuel gauge reads high also, then you have a faulty voltage stabilizer on the back of the instrument cluster. You could also confirm gauge accuracy with a mechanical gauge plumbed in the back of the head between the two rearmost intake manifold bolts - a 1974 model *should* have a 3/8'' pipe plug at that location. If it's puking water out the top, you're not filling the radiator too full, are you?

A radiator that is hot on the top and cool on the bottom is very normal, especially at low loads and/or ambient temps.

Yes, water pumps can and do wear out. The only way to know for sure is to either check the pump pressure, or else take it off and do a visual inspection. To check the pressure, insert a 0-60 PSI gauge at the temp sender location and start the engine. As you rev it up the pressure should slowly increase, to maybe 10-30 PSI or so.

Hope this helps.

 

[sotxbill]

With the cap off... and running, watch it warm up and dip your finger into the water on occasion. You should see when the thermostat opens and feel the water in the top go to warm, and then get hotter. There should be NO bubbles!!!!!!, and with difficulty, you should see some flow across the top tank all though the flow can be a bit hard to see if the top tank is full. Today on 77 4600 diesel, I was seeing about 150-158F on top and 90 to 105F on the bottom tank by using my ir-thermometer gun. This is a bit low on the bottom but its a 65 degree day and a light load on the tractor. So I am seeing a lot of cooling, more than normal........ On a 100degree day I expect to see 20 to 35 degrees between the top tank and the bottom tank. But as I said, today the bottom tank, bottom hose were barely warm to the touch. Thermostats.... some can only open fully or close fully. Others can open incrementally. I believe the one on this tractor was only opening a bit and not all the way as that is all that was needed. I try to use all the tractors that come through for farm chores if I can so I can speak better as to the condition and soundness of the tractor. And I try to shoot an IR gun at all to check the heat gauge on the cluster. This tractor does have a sticky oil pressure sender that needs replacing as it tends to stick in the safe mode unless you tap it when not running to finally get an oil light. So that is on the list.

 

[johnofnewhaven]

Well it is not puking water out of the radiator. The radiator level is what I always have it at which is like an inch or so from the top of the radiator. The temp gauge is reading high in the red. The fuel gauge is reading just about right. I don't have the gauges to check it but I guess I'll have to go pick one up somewhere. Thanks for your help

 

[Roger in Iowa]

The wobble you have can be very expensive. I would replace the water pump asap.

 

[johnofnewhaven]

Sotxbill I am out at my tractor now with my ir-thermometer. Gage on the dash is pegged in the red. I can see water flowing slowly in the radiator. Top tank on the radiator it's just under 170 bottom tank on the radiator is about 75. Top radiator hose is about 106 and the bottom radiator hose is about 68. My outside temperature here right now is about 50. I have been running the tractor at a high idle for about 15 minutes. Water pump itself is reading pretty much the same as the top tank of the radiator

 

[Bern]

I'd still bet your problem is a temp gauge issue. Look for that pipe plug in the back of the intake manifold, should be 3/8 NPT. Stick a mechanical gauge in there and compare.

OR, pull your instrument cluster out and monitor the voltage coming out of the voltage stabilizer after about a minute or so of key-on time. Voltage should fluctuate back and forth, it should not remain at a steady 13 or 14 volts.

 

[johnofnewhaven]

Will do Bern. Good advice. Thank you

 

[sotxbill]

I'm suspicious that your gauge is wrong... Your temps show to be about normal assuming you have flow. And it sounds like you do.. 170 coming out of the engine at the thermostat housing or the radiator tank is very very normal and not over heating. Makes me think you have a 180 degree thermostat?? I see a lot of heat gauges that read high and thats the reason I check everyone after a load to evaluate the cooling system. On the 5000 series a common problem is the needle on the gauge can be bent slightly,, and a tell tell sign is that when its off, the needle should go to the left and off the chart so to speak, but still be visible. If its bent it will be on the low end of the chart or cold reading.. thus it will read in the low red when the thermostat opens. And then there are the sending unit problems, voltage stabilizer module thingy and a bad ground wire on the gauge cluster also. I also see the power wire (brown or white) and the heat gauge wire (greenblue) reversed often on the back of the cluster. Since there is an a, b, and c model, there are a few differences in the wiring colors depending on where your tractor was made. On lots of clusters the gasket moves over and interferes with the heat gauge and the cluster needs to be taken apart and have the paper gasket cut away. hth

 

[johnofnewhaven]

sotxbill the gauge only goes to just the left edge of the green on the water gauge. You are correct I have a 188 thermostat. Little background on the tractor. As I mentioned I replaced the head gasket. Then I decided I was going to paint it and do a bunch more to it. I put a really good quality new wiring harness on it. It also has a new regulator. And I put a new temperature sending unit in the head. I am now beginning to thank the gauge is either off like you said or the voltage regulator is not working correctly. The dash cluster is the original. I bought a new one for it and everything worked fine except for the RPMs were way off. So I just put the old one back in it. I'm convinced now it's not overheating but I am going to put a mechanical thermostat gauge on it.

 

[Sean in PA]

(quoted from post at 12:11:03 12/10/23) sotxbill the gauge only goes to just the left edge of the green on the water gauge. You are correct I have a 188 thermostat. Little background on the tractor. As I mentioned I replaced the head gasket. Then I decided I was going to paint it and do a bunch more to it. I put a really good quality new wiring harness on it. It also has a new regulator. And I put a new temperature sending unit in the head. I am now beginning to thank the gauge is either off like you said or the voltage regulator is not working correctly. The dash cluster is the original. I bought a new one for it and everything worked fine except for the RPMs were way off. So I just put the old one back in it. I'm convinced now it's not overheating but I am going to put a mechanical thermostat gauge on it.

Now I am totally confused. When originally asked about the symptoms, you responded "The temp gauge is reading high in the red." Now you are saying "the gauge only goes to just the left edge of the green on the water gauge.". Which is it?

 

[johnofnewhaven]

Hi Sean. If you read sotxbill post we
are talking about when the tractor is
totally cold cold. He was saying when
the tractor is totally cold the water
temperature gauge should be pretty
much all the way to the left and just
visible. When the tractor is hot it
is clear up in the red almost all the
way to the right. He was just trying
to tell me that the gauge needle
could be bent or messed up. I can see
how it would be a little confusing.

 

[Eman85]

You said you repalced the sending unit for the temperature gauge.
Any reason? Still have the old one?
I don't know the OHM reading range of the temperature sending units on these tractors, maybe somebody does. Generally if you unplug the sensor the gauge goes full cold and when you ground the wire it goes full hot. If you know the OHM readings you can test the gauge with resistors.

 

[johnofnewhaven]

I replace the sending unit because
the terminal tab on the end of it was
broken off.

 

[Sean in PA]

Sorry for the confusion on my part. If the needle doesn't go all of the way to the left when the key is off, then there is something wrong with the gauge itself. When there is no current through the windings at the base of the needle, it is not acting as an electromagnet and therefore it should return to the far left position. It normally takes an electric current through the windings in the base of the needle to get it to deflect from the full left position.

 

[johnofnewhaven]

I will unhook the battery and see
what happens. The gage dash cluster
is the 50 year old original.

 

[sotxbill]

The new sending units are not correct.. at least in my experience in the last couple of years. That would be my very first suspect. It seems that they are all over the map when it comes to correct resistance. I cant find the resistance spec for the correct sending unit, but they give you the correct resistance at given temperatures. I'll look through my books but its been a while. there were also dots on the bottom of the gauge to help check the calibration at known resistances on some of the gauges. I would try your old sending unit first off, and see if that moves the gauge back to correct readings... assuming we're going the correct direction. Just also thinking it could also be all the aftermarket clusters that are part of this wonky sending unit problem I've been seeing.

 

[sotxbill]

taken from another post from 2017.. dont know if it is correct reading or not, but it gives you an ideal....

I have a 1974 Ford 3000 (diesel) that after a few minutes of running the temperature gauge always reads in the red and beyond the max scale. I have just replaced the water pump, thermostat (192 deg F) and radiator. I have also tried two different temperature sending units both with the same results. The tractor runs at expected temperatures based on IR thermometer readings. The fuel gauge works properly and I feel I don't have any electrical issues like voltage stabilizer or regulator problems. The temp. gauge responds to differences in resistance but I am thinking either there is something wrong with the gauge or it does not match my temperature sending units. Here are some resistance readings from the sending unit to battery negative terminal. Tractor cold - 600 ohms and gauge on full cold. Gauge at lower end of red - 42 ohms. Gauge at upper end of red - 40 ohms. Tractor running at normal operating temp. after thermostat open - 28 ohms. Can anyone tell me what the ohm reading should be at normal operating temperature and at the lower end of the overheating (red) level? I cannot find those numbers anywhere in manuals or online. Thanks.

 

[johnofnewhaven]

sotxbill the terminal blade broke off my old sending unit. I currently have the old dash cluster in. I will order another sending unit from a different vendor and see what happens. I'm still thinking I'm just going to put in a mechanical temperature gauge. I think I'd rather have that because then I can actually see what the temperature is.

 

[sotxbill]

Taken from an earlier post from Hobo...

I have that info in the shop will have to check it tomorrow.

1969 ford 3000 temp diesel if it makes a difference.
Low/cold 360 ohms at 60 deg
mid 100 ohms
hot center of red 50 ohms

Also notes that the ground on the back of the cluster must be good as the rivet on the spade lug can be loose or corroded.

also thanks to Hobo...
Fuel sender 1969 ford 3000
empty 210 ohms
full 17 ohms
This post was edited by Hobo,NC on 07/26/2023 at 08:55 am.