Stumped - Mustang 5.0 running hot lean

[AGGRV8D]

If its a head gasket issue i can see that but a coolant check could prove that. If the total timing is out i can see that.,if you have a fuel pressure issue i can see that. At this point i would be checking for a plugged exhaust or plugged cat especially if you have sluggish performance problems. I dont under stand a head or valve problem as those parts dont change in use making an engine run hot.

Exhaust is dual full length headers, recently ceramic coated and dual 2.5 inch Flowmaster Mufflers w/ turn downs just before the rear axle. No Cats or any other b.s. to keep it from breathing. The exhaust seems to be breathing great, especially with the new ceramic coated headers.
But the damn car still overheats... and only under a heavy load.

 

[Rustytruck]

I wish you didnt have an electric fan. I fear at engine speed it is metering air flow not contributing air flow.at this point i would try running with the hood off. It might help at solving this problem. If it runs cooler with the hood off then it points to an air flow issue.

 

[surfer-b]

The only thing that would cause it to overheat under load the way u hav described is lack of coolant flow/airflow, or vacum leak, also the coolant temp sensor can cause odd issues, but mostly flooding because it usually sends a signal to PCM that it's -40 temp an adding lots of fuel

 

[AGGRV8D]

The thing is it ran fine with that fan and setup for years, then this issue came up and seems to be getting worse, but maybe that’s just my frustration.

Has anyone experienced issues w/ their Spal Fan degrading in efficiency over time? Checked/replaced all relays switches and fuses. It is definitely coming on (even tested as constant on and still overheated).

If I want to attempt converting to mechanical fan, what’s that entail (clutch and fan blade?)? It’s a ‘91 5.0 H.O. w/ front assembly off a ‘98 Explorer (I believe). Don’t think the explorers came w/ a mechanical fan, does that mean new pulley? going back to a mustang front assembly?

 

[AGGRV8D]

The only thing that would cause it to overheat under load the way u hav described is lack of coolant flow/airflow, or vacum leak, also the coolant temp sensor can cause odd issues, but mostly flooding because it usually sends a signal to PCM that it's -40 temp an adding lots of fuel

Sound advice

99% ruled out waterflow issue

Going to try the Hood Trick, see what that does... If it’s any cooler then I’ll start w/ a new fan, then start drilling breather holes anywhere I can .

What drives me nuts is it wasn’t an issue for years and years, then popped up seemingly out of nowhere.

 

[DirtDonk]

Yeah, that's the strange part. And no, I have not heard of Spal fans (or any others really) degrading over time to this extent. And I would think you'd hear it in the way it runs.

If it's truly an Explorer front accessory drive, you need only get an Explorer fan clutch and fan. They were all mechanical. I believe it was the early ones that were metal fans, while the later ones were plastic. Both of them very effective and efficient.

But if it's not an Explorer front end, then they won't fit. They must screw on to the threaded end of the water pump. No bolts, just spin-on.

Got a pic of the front end? Explorer stuff was very distinctive and different from all the others except for one of the Mustangs. I had thought it was the '94/'95 model, but I have been proven wrong a couple of times on that when we looked at those setups.
I just remember seeing a listing for a Mustang water pump that had the same design and specs as the Explorer pump.

If we see pics, we can determine if it is or not.

Paul

 

[AGGRV8D]

Here are a few pics, can get more

 

[ransil]

I will throw a few thing out

what is in from of the radiator?

Pull codes

fan should be ok fans job is to cool at low speed,under 20 mph
at highway speed should have enough airflow to cool it.

backwards thermostat
lower hose sucking shut
lean running
maf contaminated by oil from K&N
turbulent air over maf, put a shield over the air filter
need a bigger air gap between maf and throttle body.
too much timing, what is total advance?
I'm Not a fan of aftermarket ignition systems
O2 sensors on the wrong bank

 

[AGGRV8D]

I will throw a few thing out

what is in from of the radiator?

Pull codes

fan should be ok fans job is to cool at low speed,under 20 mph
at highway speed should have enough airflow to cool it.

backwards thermostat
lower hose sucking shut
lean running
maf contaminated by oil from K&N
turbulent air over maf, put a shield over the air filter
need a bigger air gap between maf and throttle body.
too much timing, what is total advance?
I'm Not a fan of aftermarket ignition systems
O2 sensors on the wrong bank

If you go back through the thread you’ll see that those have almost all been dismissed as possible causes.

 

[AGGRV8D]

If you go back through the thread you’ll see that those have almost all been dismissed as possible causes.

We’ve tried going back to stock coil, replaced all sensors (MAF, O2) multiple times. Replaced coil 3 Times. All new hoses. Pressure tested radiator and went through entire cooling system.

 

[AGGRV8D]

Here are a few pics, can get more

Also, have a longer intake tube to move MAF sensor at least 10” from throttle body. I know this is the thing to do, but not what’s causing the overheating as it was run like this for years with no issue.

 

[surfer-b]

That is an Explorer front dress, the explorer clutch an fan will work, but Like I stated earlier, for the setup to work the best the fan needs ~ 3/4" showing all the way around, that's the way the Ford engineers designed it, this is the way I have ran mine and never had any problems with cooling, even her in the SE with all the heat and humidity. With that said Im not saying that is your problem but you say you are 99% sure its not a coolant problem, that only leaves airflow or vacum leak.

 

[Timmy390]

Did you ever pull codes or try to? Reading back through this thread you said you didn't see a port to pull codes. Has anyone you taken it to pulled codes?

You need a reader like this (It's the one I use)
https://www.amazon.com/INNOVA-3145-...ocphy=9025754&hvtargid=pla-434264198620&psc=1

and the port will be someplace under the hood left side
https://www.2carpros.com/articles/f...gnostic-trouble-code-definition-and-retrieval

My 95 Stand EFI also uses OBD1 and I wired a CEL into the dash so know when something isn't right. If it's running lean, the O2's should be telling you. When I had a massive vacuum leak my CEL came on. Also had a TPS issue that caused a rich condition. CEL caught it too.

ALSO, maybe reach out to EFIGuy and see about doing some data logging remotely.

Have you changed the BAP sensor? check the vacuum like to it?

Tim

 

[DirtDonk]

Just throwing out a wild-assed question. Is that a transmission cooler on the fender? Could the fan have stopped working and so the transmission is adding more heat to the system then it was before?

Long shot from way out in left field maybe, but at this point we have to really dig for a reason. Because it ran so well for so long before, maybe some outside influence is at work.

Paul

 

[AGGRV8D]

Just throwing out a wild-assed question. Is that a transmission cooler on the fender? Could the fan have stopped working and so the transmission is adding more heat to the system then it was before?

Long shot from way out in left field maybe, but at this point we have to really dig for a reason. Because it ran so well for so long before, maybe some outside influence is at work.

Paul

It’s an oil cooler. Also have an external cooler for power steering.

 

[AGGRV8D]

Had the Radiator flushed and pressure tested, but considering swapping it just to see what happens. Before I drop $500-$1000 on a new radiator, does anyone have any feedback on the Ron Davis radiators and/or removing/modifying the core support for a totally custom (larger) radiator setup?

 

[ransil]

Ron Davis cost too much..
Explorer Radiator can be had for $100