My 1984 F150 2wd Flareside Project "Blue Mule"

[Gary Lewis]

I just got this thing fired up in the truck. Starting it was no problem at all, but now it's overheating...at least according to the factory gauge. Upper rad hose is hot, but the lower rad hose is still cold next to the steering box.

Is it possible that I have the thermostat in backwards? Or, what else? The temp sensor is an aftermarket one, so maybe it is not correct?...

Any suggestions on how to check and see what's going on?

It is very possible to have the thermostat in backwards. The spring and the works go down into the block. And, it is possible the 'stat stuck.

To check for overheating, use a non-contact, aka IR, thermometer on the base of the thermostat housing.

Aren't you glad you broke it in on the dyno? Otherwise you'd risk damaging the cam by stopping the engine while it was breaking in.

[Rembrant]

To check for overheating, use a non-contact, aka IR, thermometer on the base of the thermostat housing.

Aren't you glad you broke it in on the dyno? Otherwise you'd risk damaging the cam by stopping the engine while it was breaking in.

Gary, I ended up doing just that, and it tested OK. It was still behaving weird, so I think I may have had some air pocket issues and once they were worked out of the system, it all settled down a bit. I still have an issue with the sender, or the gauge, or the wiring/connections in between. The gauge was reading well into the "H", and is still reading too hot. I'll sort that out, no big deal.

The FSM says to check the gauge with resistors. A 10 ohm resistor to ground should put the gauge at the end of the range closer to the "H", and 73 ohms should put it closer to the "C". If the gauge behaves fine with that test, then replace the sender. The sender was reading around 30 ohms when I checked it, which should have put it in the middle of the gauge-ish...but it was still on the hot side of the gauge. With all of the corroded wires and connectors I'm finding on this truck, I'm surprised that was the only issue I've run into that actually made me worry...even if it was only briefly.

And yes, that is why I paid the extra to have the engine broken in and tested on the dyno. They put a lot of effort into making sure everything was right before they started it. If I was at the beginning of a 20 minute cam break-in and saw the temp gauge pegged hot, I would have had to shut her down (having not been prepared with a IR temp gun on hand).

 

[Gary Lewis]

To check for overheating, use a non-contact, aka IR, thermometer on the base of the thermostat housing.

Aren't you glad you broke it in on the dyno? Otherwise you'd risk damaging the cam by stopping the engine while it was breaking in.

Gary, I ended up doing just that, and it tested OK. It was still behaving weird, so I think I may have had some air pocket issues and once they were worked out of the system, it all settled down a bit. I still have an issue with the sender, or the gauge, or the wiring/connections in between. The gauge was reading well into the "H", and is still reading too hot. I'll sort that out, no big deal.

The FSM says to check the gauge with resistors. A 10 ohm resistor to ground should put the gauge at the end of the range closer to the "H", and 73 ohms should put it closer to the "C". If the gauge behaves fine with that test, then replace the sender. The sender was reading around 30 ohms when I checked it, which should have put it in the middle of the gauge-ish...but it was still on the hot side of the gauge. With all of the corroded wires and connectors I'm finding on this truck, I'm surprised that was the only issue I've run into that actually made me worry...even if it was only briefly.

And yes, that is why I paid the extra to have the engine broken in and tested on the dyno. They put a lot of effort into making sure everything was right before they started it. If I was at the beginning of a 20 minute cam break-in and saw the temp gauge pegged hot, I would have had to shut her down (having not been prepared with a IR temp gun on hand).

Air pockets can cause big problems. I like to fill a cooling system with a heater hose off at the heater. That let's the air out as it is the high spot in the system.

But to the gauge, corroded wires shouldn't cause the gauge to read high. Instead, it should read low as that would increase the resistance, and low resistance causes the it to read low. But, if there's a short circuit then that might do it.

[Rembrant]

But to the gauge, corroded wires shouldn't cause the gauge to read high. Instead, it should read low as that would increase the resistance, and low resistance causes the it to read low. But, if there's a short circuit then that might do it.

Yes, good point, thanks Gary. I guess I was just thinking in general terms, that the condition of the wiring in this truck is a bit sketchy, so I don't know what I'll find next;).

 

[Rembrant]

But to the gauge, corroded wires shouldn't cause the gauge to read high. Instead, it should read low as that would increase the resistance, and low resistance causes the it to read low. But, if there's a short circuit then that might do it.

Yes, good point, thanks Gary. I guess I was just thinking in general terms, that the condition of the wiring in this truck is a bit sketchy, so I don't know what I'll find next;).

Looks like the old Blue Mule is back on the road!

I put 30-40 miles on it today, and it's working great! The exhaust is leaking and it is stupid loud, but I will deal with getting that all fixed up and quieted down a bit.

The used M5OD I installed seems to be OK, and it is not leaking. I guess I installed the seals properly...lol.

I love the floor shift, and having 5 gears instead of 3. It sure makes the truck nice to drive. I love it. Once I get the exhaust fixed, and install a new steering box (redhead or bluetop) this old truck is going to be a hoot to drive.

With the 5spd and the 3.08 gears, this thing flies on the highway! It hits 70 MPH without even trying to.

Anyhow, I just wanted to say thanks to all who helped me with all of my questions (Especially Gary! A tip of the hat to you for all the time and effort you put into this site!). I assure you it is certainly appreciated.

Next winter will hopefully be rust repair and paint. We'll see how it goes, but for now I'm mobile;).

[Gary Lewis]

Looks like the old Blue Mule is back on the road!

I put 30-40 miles on it today, and it's working great! The exhaust is leaking and it is stupid loud, but I will deal with getting that all fixed up and quieted down a bit.

The used M5OD I installed seems to be OK, and it is not leaking. I guess I installed the seals properly...lol.

I love the floor shift, and having 5 gears instead of 3. It sure makes the truck nice to drive. I love it. Once I get the exhaust fixed, and install a new steering box (redhead or bluetop) this old truck is going to be a hoot to drive.

With the 5spd and the 3.08 gears, this thing flies on the highway! It hits 70 MPH without even trying to.

Anyhow, I just wanted to say thanks to all who helped me with all of my questions (Especially Gary! A tip of the hat to you for all the time and effort you put into this site!). I assure you it is certainly appreciated.

Next winter will hopefully be rust repair and paint. We'll see how it goes, but for now I'm mobile;).

Congrat's!!!!

But, be careful at that speed! Wow, hard to believe it'll run that fast at less then 2000 RPM. At 2500 RPM Big Blue is doing 65 MPH. And I don't want to think about how much of a handful he'd be at your speed.

As for the help, happy to do so. Helping someone get his/her truck back on the road, like you've done, is what it is all about.

[Rembrant]

But, be careful at that speed! Wow, hard to believe it'll run that fast at less then 2000 RPM. At 2500 RPM Big Blue is doing 65 MPH. And I don't want to think about how much of a handful he'd be at your speed.

Well, that's 100 km/hr...so only about 60 MPH...not that bad really. Although, with that sloppy reman steering box, it can be a bit unnerving sometimes at any speed if you hit a bump or groove in the road.

The reason for taking that picture was to show where the RPM's landed at 60MPH, and it was just under 2000 RPM. I had calculated this anyway, but I'm just happy that it worked as planned...lol. The M5OD 5spd obviously has a speedo drive gear with the same amount of teeth as my 3spd did, because my speedo appears to be reading correct...or at least as correct as it was prior to swapping in the 5spd. I was pretty certain that the speedo was going to be correct, but I can say now that it is confirmed.

 

[Gary Lewis]

But, be careful at that speed! Wow, hard to believe it'll run that fast at less then 2000 RPM. At 2500 RPM Big Blue is doing 65 MPH. And I don't want to think about how much of a handful he'd be at your speed.

Well, that's 100 km/hr...so only about 60 MPH...not that bad really. Although, with that sloppy reman steering box, it can be a bit unnerving sometimes at any speed if you hit a bump or groove in the road.

The reason for taking that picture was to show where the RPM's landed at 60MPH, and it was just under 2000 RPM. I had calculated this anyway, but I'm just happy that it worked as planned...lol. The M5OD 5spd obviously has a speedo drive gear with the same amount of teeth as my 3spd did, because my speedo appears to be reading correct...or at least as correct as it was prior to swapping in the 5spd. I was pretty certain that the speedo was going to be correct, but I can say now that it is confirmed.

Oops, missed that.

[Rembrant]

My Bronco with a stockish 302 is running 33" tires with 4.10 gears behind the NV3550. That's equivalent to 3.35 gears and 27" tires. I really like the setup because, like you, I don't want it screaming on the highway. But most people tell me that I shouldn't "fear the gear" and that it would be a lot better with lower gears. I don't doubt that it would pull stronger, and probably wouldn't even get significantly lower mileage with 4.56 gears (equivalent to 3.73 with 27"). But it would be buzzier, and I'm happy enough with the performance I have.

But that gearing will make your new-found power harder to find. If it was me (and I know it isn't!) I'd want to be able to get at that power easier (even though I probably wouldn't use it a lot). And with 27" tires and a 5 speed OD trans I'd probably go about 3.73 gears.

I think you're right on the 3.08 diff gearing being too tall for the 302/5spd. It's not awful or anything, but it would certainly be better geared a little lower. I've been driving the truck a little, and it's lugging a bit below 2000 RPM. Above 2000, it lights right up. I won't be doing anything with it this year, but perhaps this winter I will make it part of my to-do list.

A lot of the driving I will be doing with this truck is at about 50MPH, and as it is now, 3rd feels too low, and 4th too high. Same thing with the highway speeds. Then the issue is between 4th being too low, and 5th, too high. The truck will do 80MPH like nothing at all, but I want to drive more like 65MPH, which feels like it's revving too much in 4th, and not enough in 5th.

My current issue(s) are the exhaust and the steering, so I haven't been able to get a 100% proper feel for the truck yet. My exhaust is still way too loud, so that aggravates the issue of the engine not being in it's sweet spot. To rev the thing in neutral or to drive it through the gears above 2000 RPM or so, it sounds fantastic, but lugging along below 2000RPM, it sounds just awful, and is way too loud. The steering on the other hand is still way too sloppy...that new reman box has to go. It's sloppy enough it is a bit unnerving to drive with the way the roads are around here. I must install one of those RedHead or BlueTop boxes, and I'm even going to add a stabilizer to it. They're cheap enough it probably wouldn't hurt.

None of it is a big issue at the moment. I don't need to drive the truck, it is just a weekend play toy, and it is going to take some time to get all the wrinkles ironed out of it.

[Gary Lewis]

My Bronco with a stockish 302 is running 33" tires with 4.10 gears behind the NV3550. That's equivalent to 3.35 gears and 27" tires. I really like the setup because, like you, I don't want it screaming on the highway. But most people tell me that I shouldn't "fear the gear" and that it would be a lot better with lower gears. I don't doubt that it would pull stronger, and probably wouldn't even get significantly lower mileage with 4.56 gears (equivalent to 3.73 with 27"). But it would be buzzier, and I'm happy enough with the performance I have.

But that gearing will make your new-found power harder to find. If it was me (and I know it isn't!) I'd want to be able to get at that power easier (even though I probably wouldn't use it a lot). And with 27" tires and a 5 speed OD trans I'd probably go about 3.73 gears.

I think you're right on the 3.08 diff gearing being too tall for the 302/5spd. It's not awful or anything, but it would certainly be better geared a little lower. I've been driving the truck a little, and it's lugging a bit below 2000 RPM. Above 2000, it lights right up. I won't be doing anything with it this year, but perhaps this winter I will make it part of my to-do list.

A lot of the driving I will be doing with this truck is at about 50MPH, and as it is now, 3rd feels too low, and 4th too high. Same thing with the highway speeds. Then the issue is between 4th being too low, and 5th, too high. The truck will do 80MPH like nothing at all, but I want to drive more like 65MPH, which feels like it's revving too much in 4th, and not enough in 5th.

My current issue(s) are the exhaust and the steering, so I haven't been able to get a 100% proper feel for the truck yet. My exhaust is still way too loud, so that aggravates the issue of the engine not being in it's sweet spot. To rev the thing in neutral or to drive it through the gears above 2000 RPM or so, it sounds fantastic, but lugging along below 2000RPM, it sounds just awful, and is way too loud. The steering on the other hand is still way too sloppy...that new reman box has to go. It's sloppy enough it is a bit unnerving to drive with the way the roads are around here. I must install one of those RedHead or BlueTop boxes, and I'm even going to add a stabilizer to it. They're cheap enough it probably wouldn't hurt.

None of it is a big issue at the moment. I don't need to drive the truck, it is just a weekend play toy, and it is going to take some time to get all the wrinkles ironed out of it.

If you can quantify what RPM is the sweet spot for the engine, where it feels like it is lugging, and where it feels like it is buzzing then you can put together a chart of what rear gears put it in its sweet spot in each gear at what RPM. Or, you can back into it if you don't know the RPM by noting the MPH that feels like the sweet spot in each gear, and then multiply the MPH by your current gear ratio of 3.08 and divide by the new ratio.

For example, if it feels good at 80 MPH in 5th, then with 3.55's it would like 69 MPH, and with 3.73's it would like 66 MPH.