79 FJ40, first test drive at 60mph - gear noise, water temp increase questions (7 Viewers)

[CruiserInProgress]

I finally got my rusty 79 desmogged FJ40 project road worthy, sort of, and put tags on her. She had been sitting for more than a decade and abused before that.

After a lot of tinkering and some new parts it seems to start well, idle well, accelerate well, doesn't smoke, shifts well (2wd and 4wd) and tracks well. The brakes are next on the list, but it seems to stop OK with the old stuff.

It came with a lift and 15x33 BFG tires, and I upgraded to a FJ60 ignition, but the rest of the drive train seems to be mostly stock (desmogged 2F engine, 4speed gearbox) and stock diffs based on highway performance numbers. I have changed gear oil in both diffs, gearbox and transfer case. The fluids were dark and kinda bubbly, but no metal chunks found.

So, during my first highway test drive this afternoon, two things concerned me:

1) Gearbox or transfer case whining?

In 2H, at 60mph (2500rpm) the overwhelming sound in the cab was coming from the area of the gearbox/transfer case. A high pitched whining is always there while driving, but the pitch and volume increased with speed and was even more noticeable at 60mph. I had verified previously
that the front diff is not engaged and the front drive shaft is not spinning while in 2H. Does that loud, whining sound seem normal?

2) WaterTemp Increase at highway speed?

Water temp increased from 1/3 to 1/2 on my gauge during each 60mph (1/4 mile) test run, then back down to 1/3 when I slowed. That doesn't seem right to me. The fan seems fine, the reservoir/radiator didn't boil over or smell hot and there are no apparent recent leaks. I have not yet flushed the cooling system or cleaned out that block drain, but the coolant seems clean and green. The stock oil pressure gauge indicates there is pressure. And there are no other obvious symptoms, although I may have heard a slight squealing sound from the area of the water pump.

So, what could be the issue elevating the water temp at 60mph? I kinda don't want to drive it at that speed without figuring that out first.

Thoughts?

By the way, I have read that some found driving a short wheelbase FJ40 with a lift and tall tires at highway speeds a bit "exciting". I now know what they meant.

 

[brian]

First time driving a 40series?

 

[Jdc1]

I finally got my rusty 79 desmogged FJ40 project road worthy, sort of, and put tags on her. She had been sitting for more than a decade and abused before that.

After a lot of tinkering and some new parts it seems to start well, idle well, accelerate well, doesn't smoke, shifts well (2wd and 4wd) and tracks well. The brakes are next on the list, but it seems to stop OK with the old stuff.

It came with a lift and 15x33 BFG tires, and I upgraded to a FJ60 ignition, but the rest of the drive train seems to be mostly stock (desmogged 2F engine, 4speed gearbox) and stock diffs based on highway performance numbers. I have changed gear oil in both diffs, gearbox and transfer case. The fluids were dark and kinda bubbly, but no metal chunks found.

So, during my first highway test drive this afternoon, two things concerned me:

1) Gearbox or transfer case whining?

In 2H, at 60mph (2500rpm) the overwhelming sound in the cab was coming from the area of the gearbox/transfer case, a high pitched whining is always there while driving, but the pitch and volume increased with speed and was even more noticeable at 60mph. I had verified previously
that the front diff is not engaged and the front drive shaft is not spinning while in 2H. Does that loud, whining sound seem normal?

2) WaterTemp Increase at highway speed?

Water temp increased from 1/3 to 1/2 on my gauge during each 60mph (1/4 mile) test run, then back down to 1/3 when I slowed. That doesn't seem right to me. The fan seems fine, the reservoir/radiator didn't boil over or smell hot and there are no apparent recent leaks. I have not yet flushed the cooling system or cleaned out that block drain, but the coolant seems clean and green. The oil pressure gauge indicates there is pressure. And there are no other obvious symptoms, although I may have heard a slight squealing sound from the area of the water pump.

So, what could be the issue elevating the water temp at 60mph? I kinda don't want to drive it at that speed without figuring that out first.

Thoughts?

By the way, I have read that some found driving a short wheelbase FJ40 with a lift and tall tires at highway speeds a bit "exciting". I now know what they meant.

View attachment 3907002

Grab an infrared thermometer and get some actual numbers, the stock gauges are pretty vague.

 

[OlYellr]

I can’t have a conversation with myself above 65 with the noise in mine. Whine - was the tcase ever rebuilt? Thinking bearings.

I don’t have first hand knowledge but they say the split tcase that come with 8/1980 and after are quieter and stronger.

 

[CruiserInProgress]

Grab an infrared thermometer and get some actual numbers, the stock gauges are pretty vague.

An IR temperature gun is probably a good addition to the shop.

I wasn't even sure the gauges worked until today, when I reinstalled the speedo cluster after rewiring my harness.

But, even if the temp gauge isn't accurate, to see a marked increase in temp (from 1/3 to 1/2 needle deflection) at 60mph was concerning.

On one hand, the engine is working harder at higher speeds. But on the other hand, there is more air pushing through the radiator, which should help cool the engine. Still curious why the increase.

 

[Jdc1]

An IR temperature gun is probably a good addition to the shop.

I wasn't even sure the gauges worked until today, when I reinstalled the speedo cluster after rewiring my harness.

But, even if the temp gauge isn't accurate, to see a marked increase in temp (from 1/3 to 1/2 needle deflection) at 60mph was concerning.

On one hand, the engine is working harder at higher speeds. But on the other hand, there is more air pushing through the radiator, which should help cool the engine. Still curious why the increase.

There is almost a 20* difference between my Dakota sender in the stock location and the Sniper sender in the block drain, it’s all good and will cruise at 65mph for extended periods. Yours might be ok but without actual numbers you are flying blind.


You’ve got some serious heavy hitters reading as I type, hopefully they’ll weigh in.

 

[CruiserInProgress]

I can’t have a conversation with myself above 65 with the noise in mine. Whine - was the tcase ever rebuilt? Thinking bearings.

I don’t have first hand knowledge but they say the split tcase that come with 8/1980 and after are quieter and stronger.

I was expecting more tire noise, engine noise and wind noise, and all of those were there, but the whining gear was much more noticeable than any if those other noises.

I may have been hypersensitive to seemingly odd noises on this highway run due to the truck's history and work done. Kinda driving with fingers crossed!

Plus, although I have used an 80 series, then a 100 series as my primary transportation for the past 25 years, this is my first 40 series, which is a totally different beast.

Not sure if that whining gearbox is typical (high speed or low speed) or if I should be concerned.

 

[rkymtnflyfisher]

But, even if the temp gauge isn't accurate, to see a marked increase in temp (from 1/3 to 1/2 needle deflection) at 60mph was concerning.

It would be a good idea to get an actual temperature gauge that is reliable and will give you an actual temperature rather than some random line that could be 175F or 275F.


I destroyed an engine relying on the factory gauge, thinking the "halfway" mark was probably normal operating temperature.

I was wrong.

 

[rkymtnflyfisher]

The tranfer case is notoriously loud, although with the right lube it doesn't whine as much.

 

[rkymtnflyfisher]

Thick as honey in the wintertime.

 

[rkymtnflyfisher]

You’ve got some serious heavy hitters reading as I type, hopefully they’ll weigh in

You're already weighing in!

 

[cruisermatt]

Drain rear diff and refill with 140wt oil, repeat test drive, see if noise changes.
We see a lot of pinion bearings get really rusty in trucks that sit for a long time. They then get completely wiped out on first test drive.

Also, a lot of times a differential (especially pinion) noise will run right up the driveshaft which essentially a big guitar string and make it seem like powertrain.

Alternative answer you probably won’t like, these trucks aren’t exactly quiet to begin with, and overall acceptable noise level can be rather subjective.
On the flip side of that lots of people drive these around with poor brakes, worn out steering, vacuum leaks, etc and just think they are supposed to drive terribly. My point is, hard to diagnose over the internet

 

[CruiserInProgress]

It would be a good idea to get an actual temperature gauge that is reliable and will give you an actual temperature rather than some random line that could be 175F or 275F.


I destroyed an engine relying on the factory gauge, thinking the "halfway" mark was probably normal operating temperature.

I was wrong.

Yeah, I get the need for accuracy. I was pleased that all of my gauges came off the pegs, except the ammeter that doesn't move at all.

 

[CruiserInProgress]

Drain rear diff and refill with 140wt oil, repeat test drive, see if noise changes.
We see a lot of pinion bearings get really rusty in trucks that sit for a long time. They then get completely wiped out on first test drive.

Also, a lot of times a differential (especially pinion) noise will run right up the driveshaft which essentially a big guitar string and make it seem like powertrain.

Alternative answer you probably won’t like, these trucks aren’t exactly quiet to begin with, and overall acceptable noise level can be rather subjective.
On the flip side of that lots of people drive these around with poor brakes, worn out steering, vacuum leaks, etc and just think they are supposed to drive terribly. My point is, hard to diagnose over the internet

Thanks for the suggestions. It is difficult to pinpoint the source in an empty sheet metal brick...no insulation, no mats, no weather stripping, lots of rattles. But, my exhaust system works pretty well so I an hear more than I might otherwise.

And I get your point about the difficulty of determining normal noise level without physically being present. Not too many FJ40's in my area to hear for myself.

So, whining is normal on my 79, and we're just trying to figure out if it's louder than it should be?

 

[CruiserInProgress]

The tranfer case is notoriously loud, although with the right lube it doesn't whine as much.

It gets cold here too (Northern Idaho) so I opted for 75w90 synthetic for the diffs, gearbox and transfer case. Could that be contributing to the whining? Although I seem to recall the whining before I changed fluids.

 

[Pighead]

So, whining is normal on my 79, and we're just trying to figure out if it's louder than it should be?

Let's play "How loud is your truck?"

It would be interesting to baseline what mods improve and worsen road + wind noise. Care to measure the loudness of your truck at approx 60mph/100kmh and report back here? Tell us about your drivetrain and other factors that can have an effect on noise. You can download all sorts of decibel...

forum.ih8mud.com

 

[CruiserInProgress]

Let's play "How loud is your truck?"

It would be interesting to baseline what mods improve and worsen road + wind noise. Care to measure the loudness of your truck at approx 60mph/100kmh and report back here? Tell us about your drivetrain and other factors that can have an effect on noise. You can download all sorts of decibel...

forum.ih8mud.com

I missed that thread. Pretty interesting idea, using a phone app to get some idea of DB level.

During my test drive this afternoon, the general sound level didn't seem overly loud, especially compared to my motorcycle with modified mufflers.

It was mostly the hard-to-ignore gear whining that got me concerned if it was normal.

It seems as if some level of gear noise is normal and expected. I'll try to figure out if mine is excessive, and if so, what's causing it.

 

[rkymtnflyfisher]

75w90 synthetic for the diffs,

Synthetic/ non synthetic, that's part of the great debate.

I personally don't use any synthetic lube in my rig, one thing I noticed when using synthetic was everything that could leak did leak. Paper gaskets weeped oil, rubber seals leaked, and there's talk that some of the metal inside don't like synthetic.

 

[pb4ugo]

It's a gear drive tcase and tranny so it's going to whine a bit. How many miles are on it? The tranny should have gl4 in it, its compatible with the yellow parts that are in the tranny. When I approach the type of lube to use synthetic or dino, i look at what was available when these drivelines were designed and made.

 

[CruiserInProgress]

Synthetic/ non synthetic, that's part of the great debate.

I personally don't use any synthetic lube in my rig, one thing I noticed when using synthetic was everything that could leak did leak. Paper gaskets weeped oil, rubber seals leaked, and there's talk that some of the metal inside don't like synthetic.

Yeah, I've seen lots of threads, mostly elsewhere about synthetic vs dinosaur oils. I can't recall how I came to the synthetic decision for the gearing. I think it was GL4 vs GL5 for gearbox vs diffs. I seem to recall synthetic wasn't an issue for brass bearings, or something like that.

But, Rotella T6 15w40 for the engine was a combination of things; zinc content, multi viscosity for cold weather considerations, price, availability (I use it in my diesel tractor), but mostly it was its detergent qualities. Lots of burned buildup inside that engine I was hoping to "self-clean".