running hot for years

I need some help. My rig has been running hot for years. Currently I get up to 225 on the hiway on nice 75 degree days. I also tend to run hot on the trails and I really have to manage the temp on the trails by opening hood when stopped. Before anyone responds with the standard "are you running a fan shroud," here are the things I have done over the years (and please note these items were added because I was running hot; I did not begin to run hot because I added them):
1) Flow Kooler Hi flow water pump. I have since replaced this with a stock replacement due to my serpentine set-up.
2) Multiple radiators- stock, 4 core and 3 different Champion radiators
3) Stock mechanical fan (ran fine on hiway but not enough air while crawling)
4) so I added Electric Derale Fan as a result of advice from this forum (unable to run elec fan as supplemental pusher due to stock hood latch in front of rad)
5) Ran electric fan with and without shroud (currently running metal shroud)
6) Everything from straight water to 50/50 with water wetter
7) Various thermostats set-up ranging from no thermostat to 160-195 (such as the Shaw Hi Flow ones)

The only thing I have not done yet is to add the under the hood. Although, that may be a good thing to add, I just cannot figure out why some big cube, big HP engines, have no issues cooling with bone stock radiators.

Rig specs as follows:
351 with BC ceramic shortys and 2-1 3" exhaust, 4R70W, 4.56 and 35s, 2 inch BL
Engine specs:
1) stock non-roller from 1990 F250
2) Heads ported (gaskets were triple checked by multiple people to ensure they were installed correctly)
3) off road Comp Cam
4) Edlebrock intake
5) Running digital ECT gauge from EFI unit and also analog Autometer gauge
6) MSD atomic EFI. EFI parameters:
- I added mechanical adv everywhere from 2 to 15 degrees BTDC
- Added additional vacuum adv (on top of mech adv) from 0 to 15 degrees
- Have set total timing everywhere from 2000 to 3500
- Air fuel mix from 12.5 to 14.8. I have chosen different ratios used for all three positions (idle, cruise, and WOT).

So my questions are:
1) Where is your timing set (mech and vacuum?
2) What is your total timing (mine is ?
3) What RPM does your timing begin (mine is at 1100 right now)?
4) What air fuel ratio do you run?
5) Finally (and I am grasping at straws here), I have a theory that the elec fan (in puller mode) is restricting the airflow at hiway speeds. Since my fan only pulls 2400 cfm, maybe the fan is actually limiting the thousands of additional cfm that would otherwise be flowing through the rad at hiway speeds. Again, I am grasping for anything here but wondering if anybody else had a thought on that theory.

I went through all of this for years actually decades.

I finally went with the Explorer Serpentine with the wild horses flowkooler pump and a champion radiator with the inlets and Outlets reversed for the serpentine setup.

I also have an air conditioning condenser in front of my radiator further inhibiting flow but the Explorer mechanical fan sucks air through the radiator like nothing else. I only had to modify my stock rad shroud a little bit to make it work effectively cut it in half then use Plumbing strap to put it back together about an inch longer on each side than it was originally with that it practically bolted right back on.

One day I will get a more perfect shroud for it but for right now it is working fantastic. Here in Central Florida it gets stiflingly hot as I'm sure you are aware. I can sit in traffic now and it never gets above 210 where it used to get up to 240 and 245. It's not just cooler with the Explorer Serpentine setup and that Explorer fan it's far more consistent and steady.

Your theory about your electric fan holding back some cm at highway speeds is likely rather valid I've heard of that happening before

Bronconut- thanks for the info. Actually shopping for junk yard serpentines now!

Mike

Sandmann here on CB sells the Explorer Serp system as a package. Cleaned up, all bolts accounted for, etc.

Well worth checking into. He is a great guy.
Love my set up he got me.

Search for Explorer Serp here on CB and his sales thread should pop up.

And don't be fooled by any other Serpentine system on the market nothing pulls as much air as the Explorer system does.

For radiators I've had the best cooling with the bc 3-cores. I just have the standard ones from before he started selling the triple pass. Both have a 351w. Since swapping to the bc's the 66 heated up once in the mountains with the stat out. Figured water flowing too fast and not cooling. Have you ever tried one of those reverse flush kits? When the 66 motor was new it was giving me fits with the temp spiking at random times. After changing a bunch of parts with no luck I tried the reverse flush and it went away. Must've been some silicone or crud from the rebuild. I flushed the radiator and motor without luck also until I did the the reverse kit.

mgb0302 said:

Bronconut- thanks for the info. Actually shopping for junk yard serpentines now!

Mike

Click to expand...

Best deal can be had there sometimes. Good luck

A few observations and questions, in no particular order.

First, have you verified that your gauge temperatures are reflecting the real world? Such as with an infrared thermometer pointed at various spots around the water temperature sensor in the intake manifold.

1. is the engine overbored at all?
2. Yes, the electric fan is likely a detriment at higher vehicle speeds at least. Should be fine at very low speeds. But it may just not be sized large enough to keep up with your particular engine anyway. You running it with a factory Bronco shroud?
3. You might consider flushing the block/system and perhaps even using the de-rusting treatment from Evap-o-Rust. I forget what the name is, but if your block spent much of it's previous life with just water in the system, you may have some buildup. Just too hard to know with donor engines sometimes, so often it's worth a few extra bucks in chemical treatments.
4. The radiators are not likely the issue as long as they're in good shape and sized for the V8's. Even the tiny Explorer V6 radiator can cool a well-tuned engine in a Bronco.
5. Might consider checking water pressure to see what's going on inside your block. More water pressure is better. Not just "ambient pressure" based on the coolant getting hotter, but actual pumping pressure.
6. Where is the temp sensor on your engine? And what gauge are you using? Stock?
7. What are the specifications of the cam?
8. Do you use manifold vacuum or timed/ported vacuum? This may or may not make a difference, but it "can" on some engines.
9. Are the rest of the internals original, or has the engine been rebuilt?

There's a little bit of what might get us started in the right direction.
Good luck. I know it's a pain to be running hot all the time, but you're not alone. It's a common Bronco story.

Paul

hot 351

Paul,

First, have you verified that your gauge temperatures are reflecting the real world? Such as with an infrared thermometer pointed at various spots around the water temperature sensor in the intake manifold. I have not actually verified temps with an infrared. However, I am pretty sure gauge is accurate since as soon as I reached 260 on the trail once (I was not paying attention and it creeped up on me) the bottom hose clamp blew - fluid everywhere.

1. is the engine overbored at all? No
2. Yes, the electric fan is likely a detriment at higher vehicle speeds at least. Should be fine at very low speeds. But it may just not be sized large enough to keep up with your particular engine anyway. You running it with a factory Bronco shroud? Using the Wild Horses steel shroud. Unable to use their aluminum shroud because I only have a .25 inch or so before I hit the pulleys with the fan. The aluminum shroud adds .5 I think.
3. You might consider flushing the block/system and perhaps even using the de-rusting treatment from Evap-o-Rust. I forget what the name is, but if your block spent much of it's previous life with just water in the system, you may have some buildup. Just too hard to know with donor engines sometimes, so often it's worth a few extra bucks in chemical treatments. Done that. Even steam cleaned it prior to assembly (Camp Pendleton's Auto Hobby shop). Did a pretty thorough job.
4. The radiators are not likely the issue as long as they're in good shape and sized for the V8's. Even the tiny Explorer V6 radiator can cool a well-tuned engine in a Bronco.
5. Might consider checking water pressure to see what's going on inside your block. More water pressure is better. Not just "ambient pressure" based on the coolant getting hotter, but actual pumping pressure.
6. Where is the temp sensor on your engine? And what gauge are you using? Stock? Have tried sensor in two places on manifold (right behing thermostat and on driver side near cylinders 5 and 6. Running EFI so using the sensor that came with kit. Gauge is computer from my MSD EFI - also have an Autometer temp gauge.
7. What are the specifications of the cam? Comp cam
8. Do you use manifold vacuum or timed/ported vacuum? This may or may not make a difference, but it "can" on some engines. Tried both.
9. Are the rest of the internals original, or has the engine been rebuilt? Bottom end stock. Heads ported.

Thanks Paul

Sounds like you’ve checked and replaced everything outside of the motor which would lead me to suspect the motor or something in it. As a bandaid, you can pull the thermostat out or gut it. My old Chevy ran at 100-110 all the time with no thermostat. (It never had one when I got it and I didn’t know. When I pulled everything apart for something one time I realized it and put one in and it was fine - 180 all day long)

But I would really suspect the condition of the passages. They could be blocked. Either by sediment, large pieces of rust, or gasket. If the head gaskets were put it backwards (apparently easy to do judging by the number of warnings in the packaging instructions) it will overheat. Also, maybe a mistake installing intake manifold gaskets.... might be worth pulling off the intake manifold and taking a look.

Who built the engine? Have you verified the head gaskets are on correctly?

Verify you have a tab sticking out above the oil filter.

Tim

When I did my Explorer conversion I built a shroud which allowed the same amount of fan "stickout" as the stock Explorer, which is ~3/4", this setup has worked perfect. I have had 3 different radiators, a stock, 2 core champion and now a 3 core Champion and the only reason for the change is the first 2 started to leak. No matter if I am driving 75 mph down Interstate, sitting in traffic or crawling in woods the temp has never got over 195, and it gets hot an humid here in SE TN. I believe the biggest problem most have with cooling when doing the Explorer conversion is they do not set up the fan/shroud combo the way the Ford Engineers designed it. If you go with the Explorer serp, build or mod a shroud that will give about 3/4" fan showing you will have good results.

What gauge(s) have you used?

Timmy 390- 99.99999999999% sure gaskets are on correctly. Triple checked by multiple people. However, good tip on checking for the tab above the filter. Never thought of that!

Broncobowsher- running digital gauge from my EFI system as well as an analog Autometer gauge.

Assuming your temp gages are accurate { sounds like you've checked them pretty well}Too far advanced timing will cause warm temps while at highway speeds . The experts say 34 * -36 * total on the mechanical advance . As far as vacuum advance goes Ford says keep that down to 10* .
I think running lean will also up your engine temps.
Do you have a body lift ? A lift will let more air flow out of the engine compartment / box . How about venting the inner fenders and or hood?
I fought high engine temps for a few years with my Cleveland and went through a lot of steps like you . Everything helped a little but what cured it was the correct thermostat for the Cleveland motor . The incorrect one wouldn't circulate enough coolant -- so maybe a water jacket/passage blockage is the cause of your issues or not enough flow for one reason or another.

Send us a picture of your fan. For a mechanical fan the factory 7 blade is best.

I did a search and from my findings, seems running hot after adding the Atomic is almost common. Found several threads on it. Running hot after Atomic install

I don't even pretend to understand the AF ratios being discussed on some of the threads. You might want to do some reading on it. Also lots of talk about idle and timing.

Might not be the cooling system.....

Tim

Timmy390- thanks. MSD issue has been my fear. Will check into that.

Rustytruck- added links to current fan and other products (tried doing that in initial post by was having trouble).

Also, I know I can keep adding/ removing parts based on recommendations, however, I want to get to the root of the problem. I know several other individuals that run big-cube, hi-hp engines with stock radiators. Unsure why exactly I have the issues and they don't.

That cam is pretty healthy it looks like. Probably pulls real hard.
But power is heat, and maybe it's just not getting out of the cylinder heat/intake manifold area efficiently enough for some reason (like, duh, right?%)) and with the extra you do actually need more capacity than you have.
But that usually comes back to the radiator, and the ones you've been using still sound like they should be fine getting rid of that heat.

What about headers? I don't remember you mentioning them. Ceramic coated or wrapped? Reason I ask is that as someone mentioned Broncos have more trouble evacuating hot air from under the hood than most vehicles. A constantly overheating Bronco can be cooled simply by opening the hood. As I think you mentioned in the first post. We used to see lots of EB's running trails out here in the summer with their "metal bikini tops" when they'd remove the hood and strap it to the roll cage.

Because your slow-speed trail temps are high too, I have to assume at this point that your fan is just not capable enough yet.
How much flow do you feel when it's running? Can it hold a piece of paper to the grille? What about a shop rag?

Got pics under the hood for us? We like pics no matter what, but I'd just like to check out what's going on. Your shroud should be promoting air flow beyond the physical size of the electric fan, so at least the air should be coming through most of the core. But maybe the total volume just can't keep up.

I would definitely do the thermometer test. Find out what it reads at the thermostat housing, both in front of and behind, then at the top of the radiator and then at the bottom.
I would think you'd want to see at least a 20° drop from top to bottom. But there is an exact specification for that, so someone here may know what that is.

Mine won't get above 175-180 (with a 195 t-stat) now until I've been on the freeway for over twenty minutes. And even then it just creeps up on normal temps if it's not a really hot day.
It used to run a straight 195 all day long, with the occasional jump above or below by about 10 degrees. After installing the Triple-Bypass (my own name for it) radiator the temps would not even climb to normal.
This is a stock Explorer engine, vs your big-cammed performance model, but it does at least highlight that changing the radiator can make a difference. One of these days I'll bother to check the difference between inlet and outlet temps.

Maybe you can start there at least, and then start blocking off air flow escape paths (around the radiator for instance) and see what you find.

Paul

No mention of fan shroud?
Ditto on fan, mechanical, stock ford with clutch probably the best bang for buck going.

Other than that, jack the nose up on the bronco a few feet and make sure all the air is out

Timmy390 said:

Verify you have a tab sticking out above the oil filter.

Tim

Click to expand...

And near the alternator on the passenger side