Thanks Larry!

I see I found this thread a few years ago and commented. I had completely forgotten about it. Thank you for reminding me. I will reach out to these guys as well.

The AFCO radiator I am using is 2 rows of 1" tubes, cross flow setup.

Thanks again!

I have a 180 degree thermostat and the highest engine temp I saw last summer was 190 in stop and go traffic with the AC on. I have the factory radiator fan and shroud, so far so good.

I talked with them today, it was a good conversation. Calling the number you had put in your post originally the gentleman there gave me the number to US Radiators parent company down the street, CGJ.

I called there, spoke with a pleasant woman named Tina. I told her what I had and the target power, she said it would likely need to be a completely custom setup. She said they could try building their standard depth radiator (3.25") using 1.5" tubes, and they could fit 7 of those in that setup. She also said they have a 5" deep unit that has 11 tubes, but also has larger tanks.

She asked for some numbers off of the stock Fiero core, and the math ran into some issues with the size of the tanks they use in both cases.

Because of this, she asked for me to do a little sketch and some dimensions and notes - I told her it would be amateur hour, and she laughed, saying they've seen things literally drawn on napkins. As long as their engineers can read my writing, they can use it to make a proper tech drawing and send it to me for review.

She did say that the rough estimate for the 3.25" deep radiator with those 1.5" tubes would be around $1000. The larger one wouldn't have a ballpark quote until they have my sketch.

So I'm working on my terribly amateur drawing and going to organize key notes in the margins, scan it and email it off with some pictures and additional commentary. We'll see what they come up with. They also offer fans and shrouds, though the ones they list (Some are by Spal) aren't pushing as much air as the Delta PAG fans.

More puttering around today. I measured the lower quarter panel as I had an idea to save Mike a little work, and that was to get some air scoops of some kind. I found some that are 11x7x3.5 (the width of the opening is 11). They have a nice lip for riveting into place. It'll be a quick addition. We discussed doing it on both sides, and getting the biggest fluid cooler we could to fit into that new space, using the pinch-weld on the bulkhead curve of the back of the cabin as the intended mounting point.

The one I found that looks good (and has the appropriate -6 AN connectors on it already) is 11x6 and will fit in there okay. It's only 0.75" thick. I asked Mike if he wanted me to find a bigger one, and we'd have to do a reducer for the AN fitting (as the larger ones are using larger AN sizes, or other fittings entirely). He said maybe and to get some options together.

He's okay if the cooler is partially obstructed by the frame/bulkhead curve, we're going to try to position it so it extends out and fills in as much of the scoop as possible. On the passenger side will be the unit for the fuel, and on the driver side we're going to put a transmission cooler there, and take the one up front out of the 'stack' of coolers.

He said I shouldn't need to worry about getting ones with fans, since we'll have good air flow except when sitting still.

I might order the scoops now (and maybe sacrificial quarter panels from the Fiero Store), but I'll hold off on the coolers until he's done with his buddies Grand National and is able to work on my car again. I have a suspicion plans might change a little again after we get the scoop setups done. We'll see!

On the radiator side, Delta PAG is backordered on their NPT temp sender. They have a 'probe' option that would stick into the fins by the outlet tube but Mike would rather not use that style.

I need to finish up my terrible drawing and notes to send over to CGJ (US Radiator's parent company) so they can quote me on some options. This might make it work out about the fan. If the unit they make me is an 18" tall core, the 18" fan will be right at the edge of the radiator, which is both good from a coverage aspect, and not good from a mounting and shroud standpoint. So I'll wait to see what CGJ comes up with before I order the fan. They have a 16" one that also moves more CFM than Spal units I've looked at.

I swapped in my instrument cluster today, connecting just the C3 connector. Temp gauge still did nothing. Mike said "We ohm'd out the wire going to the connector." to which I replied "We ohm'd out A wire going to the connector. You had me look it up. I could have looked at the wrong diagram, who knows."

I found an article on FieroFocus on how to fix the "temp gauge needle pegging issue", and that article circled the wire position on the C3 connector for the temp gauge, so next time I'm out there, I"ll see if that's what we hooked it up to. If it is, then we must have a bad sensor. Unless there's something else that would be keeping two different gauges from working.

And I did grab the current transmission and engine tunes, just so I can look at them and try to educate myself some more and ask other people more dumb questions. lol.

I took the other gauge cluster and decided to bench test the temperature gauge.

I had a wire with a resistor in it already. Some alligator clips, paper and plastic and other things to keep things isolated, and started trying to test the gauge. Resistor is in the Negative/ground wire. I am using this diagram



It says I should be using 11 and 13. The temp gauge would not move on that. So I started touching the positive to all the other pins. Temp gauge started reacting when I touched pin 15!! That's supposed to be for illumination. And no, the lights on the cluster did not light up. So, this diagram is incorrect?


I told Mike about it, so I'll bring this cluster out with the test wire I used and show him, then when he has time we'll check that out on the cluster I swapped back into the car.

Sorry for the lack of any major posts. Though I'm sure many of you appreciate not seeing so many walls of text from me.

As Mike is still busy on the Grand National, I've been putzing around with learning FAST's tuning software and playing around with the start-up tune.

Quick note on that, I emailed FAST asking about resources to learn how to tune with their software that offered "at my own pace" learning, versus a real-time class or reading what other people have done to fix specific issues and randomly trying those without knowing exactly how/why it might work. Matt over at FAST was really cool, gave me some resources, asked about what I was dealing with, offered some suggestions and even said I was welcome to shoot him another email if I was still having trouble. How awesome is that?

So besides that, I got in my scoops for the rear quarter panels. They are a quality piece, though they are obviously designed to mount on more-flat-than-the-Fiero-quarter-panel surfaces. I didn't see a good way to pie-cut/relief-cut the scoops to make them fit closer to the outside of the panel, so I decided to fit them from the back. That way any remaining gap really won't mean much.

I started by cutting out a piece of cardboard that fit in the open space of the scoop. I intentionally went with a smaller footprint, because you can always make the hole bigger, but tough to make it smaller. I was also using a 4" cutting/grinding disk to do this, so there's a few spots where the cut didn't stay 100% straight. But that's okay. This is also quasi-temporary.



As you can see, the hole is encroaching on where the baseboard trim is, so that sucks a little. It was tough to find a scoop with the exact dimensions I wanted.



Ta-da! Here it after gradually opening up the hole (and trimming the mounting lip of the scoop, you'll see that in a moment.



The joys of power tools that are effective for the task, but not ideal, in the hands of an amateur.



Here's the underside. This is where you can see I was trimming that lip to try to move the scoop as high up as possible, and keep it tucked under the ledge there.

Of course this still leads to the fastening problem. There is still a gap, though now that gap doesn't impact the function of the scoop. I need to figure out what I want to use to affix the scoop to the quarter panel at the points where they meet, so I don't need to flex the quarter panel to mate them together. I thought about industrial strength two sided tape, like what they used to put quarter panel windows on the Fiero? Thoughts?

And for the section(s) that have the gap, do they make a thicker (like neoprene or rubber) material with that same super-sticky stuff? I thought about using the 3M material that holds the lenses on the GT lamp housing, but Mike had some concerns given the potential heat in that area.

Last resort will be to use spacers to keep the gaps as natural as possible, and just bolt it all together with machine screws and metal insert locking nuts (since nylon lockers may melt).

Any other suggestions are always welcome. Once I get this one done, I'll eventually go about doing the same to the other side.

I did also revisit the cooler discussion with Mike, and said I was concerned about the increased air temps from passing through the transmission cooler then going to the intake. He thought about it and conceded it, and was just trying to come up with something that would look uniform on both sides. I said I'd rather it be optimally functional than just uniform looking. So when his attention is back on my car, we'll start workshopping that. Probably start with getting the air intake and filter setup done first, then see what we can build around it.

If we can't package the Vette one I have in there, I did see a late model Mustang stock intake setup on Craigslist that looks pretty compact. And of course there's always going the route of building a box-out for the cone filter and running it down there, similar to how FieroGuru set it up on my last Fiero.

This past Saturday was cut short, Mike was called into work.

He started to work on wiring up the Fiero oil pressure sender on his 3800 to the Fiero GT cluster to get the oil pressure gauge working, then he'd know how to do it on mine. He had labeled the wires before he did his swap, so the tan wire was already marked as 'oil pressure'. He put the '87 oil pressure sender installed, and when he would go Key-on-engine-off, the oil pressure warning light would come on, and gauge stayed at zero. He'd start the car, and the needle would bury itself, and the idiot light would turn off.

He used his voltmeter to make sure he had it wired right, looking for a change of resistance, and he is fairly sure he wired it up right. I found a few other threads on here with similar issues. One guy installed the '88 oil pressure sender, and it fixed his issue. His car was not an '88. So not sure why that worked, but hey. It's something we can try.

I finished putting the side scoop on the passenger quarter panel. To close the gap I cut strips off of the roll of HDPE (high density polyethylene) I had. Then I used 1/4-20 stainless fasteners with nylon lock nuts. It looks a little odd, but I think it's more because the scoop is all clean and hyper-white, and the quarter-panel.... isn't. lol




I also took more measurements to figure out about how much room we'll have to mount a fuel cooler in there. We'll need to relocate the oil catch can.

I'm looking at the Setrab FP119M22l . It's compact ( roughly 8" x 6" x 4.5" with the bracket), and has a fan that pushes around 350 cfm. I found a vendor that had done their own testing with it. They found that when putting coolant or water through it, temp drops were 15-30 degrees with water, and 100 degrees with oil. They do not say if they mean C or F, assuming F because something that small.

So then I poked around on Summit Racing with my estimated max dimensions (I will make cardboard standins for testing before I buy anything). I found the Derale 65840 . This one is larger, has two fans, and roughly double the CFM. No information on how effective it is. Someone even asked on Summit in the Q&A, no response, which was disappointing as Derale had replied to other questions. I emailed them directly. Their response was:

"Unfortunately, we do not have any data showing how much this cooler would cool fuel or oil."

This seems strange to me. Why would a company make a cooler and not do some testing to advertise it's abilities!? Especially when some of these compact coolers (with fans) can get way north of 500 bucks. The Derale is $890.32! Spending almost a thousand dollars with no idea how effective it's going to be, with no reasonable way to return it if it performs like garbage seems insane.

I reached out to Earl's performance on one of their units with the same question, no reply at all yet.

So I'll mock up some boxes to do test fitments, and see just how crazy I want to get with this. Mike wants to make sure it's shrouded so air can't easily go around it, fan or no.

I'm still waiting on my Radiator fan. They said it would be 4-6 weeks. We are in week 8. I emailed them on Friday. No reply to that, but received an update on my order page that a UPS label was created as of Saturday. Today is Wednesday.... UPS still has not received the package. If that doesn't change by this Friday, I'll call them to see what's going on.

It sounds like your oil pressure sender is bad. If you simply ground that single wire (with the key on), the oil pressure gauge should read 0 and the warning light will be on. With the wire not connected to anything, the pressure gauge should be pegged to the right--which is what it sounds like is happening when you actually have pressure present with your current sender.

That will test to make sure your gauge is functional. Then replace the sender.

[This message has been edited by I Lean (edited 06-04-2025).]

quote Originally posted by I Lean: It sounds like your oil pressure sender is bad. If you simply ground that single wire (with the key on), the oil pressure gauge should read 0 and the warning light will be on. With the wire not connected to anything, the pressure gauge should be pegged to the right--which is what it sounds like is happening when you actually have pressure present with your current sender. That will test to make sure your gauge is functional. Then replace the sender.

I think I either typed something incorrect in my post, or maybe in a bad way to convey the right information. That is what happens. Key on, engine off, the warning light is on, needle at 0. Engine starts, the needle buries itself (and the light shuts off, of course).

I appreciate you reading and commenting, just the same. If I'm still not getting what you're saying, please let me know. Thanks!

quote Originally posted by Trinten: I think I either typed something incorrect in my post, or maybe in a bad way to convey the right information. That is what happens. Key on, engine off, the warning light is on, needle at 0. Engine starts, the needle buries itself (and the light shuts off, of course). I appreciate you reading and commenting, just the same. If I'm still not getting what you're saying, please let me know. Thanks!

That is what I understand is happening. What I'm suggesting to do, is to test the gauge by taking the sender out of the equation, and just ground the wire to the block.

Okay cool. Thank you for the clarification. I'm sorry it didn't click before.

The weather is supposed to be crap this weekend, so it will need to wait till next weekend (weather permitting!). I will try it out. Thanks!

My Delta PAG 18" fan arrived. It's very nice. They did a great job with labeling and wire organization.

Mike took a piece of aluminum tube to replace part of the radiator hose going to the intake, so we could plumb in the sensor for the fans controller. This also gave us a great chance to look at temp differences and the odd behavior we saw with temps dropping rapidly just by going to Key on, Engine Off.

Good news, my messing with the tune and throttle adjustment screw is paying off, car is starting much easier now! When it warms up it's sitting around 1100-1200, a little high, but I'll take it for now.

Sadly, even with this fan, the temps gradually climbed, just from the car sitting at idle. It took a solid 20 minutes in 85 degree (Fahrenheit) temps to crawl up to 220, when I shut it down.

When we first started it up, the delta between the water temp sensor in the intake (stock LS4 sensor) and the fan's sensor in the radiator was about 4 degrees. Makes sense with the metal tube running under the car. As the engine temp climbed, the delta grew. Here's some pictures, grouped together. What the FAST saw first, then what the fan probe saw.





So you can see the FAST was seeing 203 at this point, but the fan probe only saw 177. A 16 degree difference seems pretty crazy.

Then:




While the FAST was seeing a temp of 216, the fan probe was seeing 193. The delta grew from 16 to 23.

When the FAST saw a temp of 220, I cut the engine but left it at Accessory. The FAST temp dropped IMMEDIATELY to 203. The fan probe was at 188. So the delta shrank to 15 degrees.




Mike wants to replace the coolant temp sensor in the intake, which makes sense, but the overheating issue doesn't make sense. When the radiator intake hose is disconnected, that electric pump is GUSHING water out -- this was an accident, but it came out in a strong jet, lost about a gallon of coolant in the few seconds to go 'oh crap!' and turn the key off completely.

It's baffling and frustrating. At idle, the engine is not putting out any crazy horsepower, not at 1100-1200 RPMs. This radiator and fan should be keeping up with it. Given the force at which water expelled, I don't think we have any obstructions anywhere. If anyone has any thoughts, please let me know.

Also, if those pictures are gigantic, I'll resize and re-upload them. Just let me know.

[This message has been edited by Trinten (edited 06-20-2025).]

Vince, it is expected for the temps between the sensor in the front head (that is the stock location for the LS4) and one up by the radiator would be different. I wouldn't spend much time focused on that.

The coolant temp dropping/changing with the engine off or on, likely means one of two things:
1. When the engine is off, the water is falling away from the sensor. If it is in the stock head location, then likely means air is getting in the system. If the sensor is not in the head, then I would move it back to that location.
2. Potential ground issue between the ECM and the engine. The temp sensor should have a dedicated ground back to the ecm to avoid reading changes based on loads from other devices. If it is it grounded to the engine, then additional electrical loads could be messing with the reading when the engine is runnng.

Thanks Paul,

I think what threw me off is the growing difference of what the engine temp was and what the sensor at the intake tube to the radiator was seeing.

I believe Mike said the engine temp sensor was in the stock location, I'll confirm tomorrow. If that is the case, do you think that we still have a nasty air pocket that isn't getting out from the vacuum fill and the steam ports (which run to a surge tank)?

quote Originally posted by Trinten: Thanks Paul, I think what threw me off is the growing difference of what the engine temp was and what the sensor at the intake tube to the radiator was seeing. I believe Mike said the engine temp sensor was in the stock location, I'll confirm tomorrow. If that is the case, do you think that we still have a nasty air pocket that isn't getting out from the vacuum fill and the steam ports (which run to a surge tank)?

Vince, the other thing to keep in mind is that heat transfer from the coolant passing through the coolant tube is dependent on the difference in temperatures from the ambient air and the coolant temps. So as coolant temps increase, there will be more heat transfer, so the difference in temps between the two sensors separated by the coolant tube would not be constant. After the car has sat for a week, the water coolant should be equalized, key on to see how different they are when you know the water temp is the same. If they are different then I would start checking resistance on the grounds between the two.

The FAST sensor should not have a significant change with engine running or just the key ON.

As we have discussed in email before, I am not a fan of rear mounted coolant surge tanks. Any hoses from your engine coolant fill point and the head steam line(s), need to go to the bottom of the surge tank, the surge tank should be higher than the coolant level of the engine, the surge tank can never go empty, and the surge tank should be pressurized (as the steam lines are free flowing), or you will pull air back into the coolant system and cause issues air pocket issues.
What is your idle speed and timing?

What radiator cap pressure are you using? 220F is boiling at atmospheric pressure. The more pressure you run in the system the higher the engine can run on temperature without boiling the coolant medium. Are you using any cooling additives? Coolant is designed to retain heat not to disperse it. Water is the best cooling agent but you must add additive to protect the engine parts from rusting. I personally run this product.


Also, I know you were running the BMW water pump with the Tecomotive controller. Did you change to a Davis? The way your temps climb I believe you have air in your system and/or the system is not slowing the coolant enough for the radiator to get rid off the heat and send it back to the engine. If the pump is installed higher than the radiator it will cavitate and carry those air bubbles through the system creating havoc.

Thanks guys.

The surge tank should be the highest point for coolant. That's where Mike hooks up this device that pulls vacuum to -20psi, then the system sucks in coolant from a reservoir. We then top it off from the surge tank. Before flipping the fill lever, it does hold vacuum.

When everything is cold, Key-On-Engine-Off the coolant temps between the two sensors is zero to 1 degree.

Coolant is in the surge tank (about half-way filled) when everything is off and cold.
The surge tank has a radiator cap on it, it's 16 PS (Canton Racing part number 81-116). Could that PSI be too low?
I *think* if we moved the surge tank to the front, it would be even lower than where it's at now (you'll see some pics of it by happenstance in the pictures below).

We switched to the Davies because after talking with Tecomotive and a few other people, they agreed the BMW pump I had was not sufficient, and pointed out how BMW guys that start modding their engines try to shoehorn in the next step-up of the BMW pump. Unfortunately that pump is not commonly available like the one I had, and it was more expensive than the Davies pump (by a considerable amount. Plus the Davies pump doesn't need a controller of any kind, so we switched to it. It does mean I still need to worry about the pump dying and not having an immediate replacement, but I'll buy another to keep in the car before going on any long trips.

I did add a bottle of surfactant (Water Wetter) to the coolant when we filled the system last year.

I asked Mike if it's possible if any obstruction could be in one of the channels in the engine (like a Mudgobber that got in there before we closed it up), he said it's unlikely, and given that we haven't warped either head or blew out a head gasket, and coolant flow seems good, he doesn't think that's an issue.

I'm going to see if anyone has a good thermal camera I can borrow, so we can check for unusual hot or cold spots.

This past weekend Mike was fixing lights, wiring, and PM on hubs/brakes on a used trailer he bought that he's using next weekend, so we just worked on mounting the exhaust fan on the unpainted decklid vent I bought from the Fiero store.



In the end we went with my original idea, which Mike wasn't thrilled with, which is to run bolts through the 'fins'. He wanted to weld in some better brackets. He took the vent and sanded off the bronze-ish coating off of one of the rivet stubs, beveled it, and tried to fill it with weld. The metal was not happy. It just sort of melted. He figures the alloy they used is basically junk "pot metal" which has a low melting point and is great for mass producing non-structural metal parts.




When he started to drill out the holes for me, the metal just flaked off, it never generated any 'strands' like you see with aluminum or steel. Flaking metal is another sign of it being pot metal.




So I used some stainless button head bolts and nuts for test fitting. The nuts I had handy were nylon lock nuts, so they need to be swapped out.






Then I did a final test fit. Everything clears!






Here's some underside shots, where you can see the clearance of the fan, and the surge tank in the foreground.