1993 Damon Intruder/P30 454 Overheating

[ThorValhallan]

Hey guys, hope y'all are doing well. We're having some issues with our 1993 Damon Intruder with the big block in it. For some background, last summer we were road tripping across some of the north western states. On the way back home thru Wyoming we ended up throwing a blade from the clutched fan thru the bottom left of the fan shroud. Luckily it didn't have any issues getting us home, and had missed everything important. Simple fix right? Just replace the fan and all should be well. Weeeell, that hasn't been how it worked out. We had a heavy duty shop (an expansion shop of Houska Automotive if you know them) replace the fan because I didn't have the time to do it myself and with all the old brittle plastic I was worried about breaking things. Got the new OEM-alike fan in (5 blade offset), and it can't get down the road without pegging the gauge and blowing boiling water out of the overflow. Uh oh. Back to the shop. That was about 2 months ago, and they've basically replaced the whole cooling system since and it's still boiling water out of the overflow and pegging the gauge.

A list of what was replaced:

Engine fan (think a stress fracture caused the fan blade to dip out)

Engine fan clutch, Heavy Duty (Idk if the clutch that's on it is right for the application, not sure of the cause but I'm pretty sure it's not engaging cuz I distinctly remember the sound it used to make. RockAuto and GmPartsWearhouse recommend a severe duty)

Thermostat (Should be OE temp, whatever that is)

Rodded the Radiator (Maybe even with a rodding this radiator still isn't pushing enough heat out?)

Water pump (I'm wondering if the shop fixed the original problem and then created a new one with this. Iirc there's two pumps available, reverse rotation for serpentine systems and normal rotation for V-belt. I believe our P30 is outfitted with v-belts, so if they put in one for a serpentine system I imagine that would be an issue)

New radiator cap (15 or 16 pound I believe)

I believe the hoses have been replaced, but I'm not certain

Also, the electric condenser fan does work. Obviously it's not moving enough air by itself to keep the engine cool. I'd read that dirt and dust can clog the space between condenser and radiator, but I'd assume the shop would have cleaned that space out when they had the radiator rodded.

So, eventually it overheats at idle. If you drive it it just heats up quicker, which perplexes me, because I would think if it was a clutch issue the temps would get better at speed. Is this generation supposed to engage the clutch even at highway speeds? I had read that the clutch only engages up to a certain RPM and speed, but that may be incorrect or outdated or just not applicable to this application. Any insight would be great. Yesterday I covered the hole in the shroud (which I hadn't realized might be a problem until recently) with some aluminum tape, maybe thinking covering the hole would get the clutch to engage. No dice. The next thing I'm thinking of trying once we're home tomorrow is disengaging the end of the spring from the front of the clutch and seeing if I can engage it manually. My best guess currently is that the engine is overheating because the clutch isn't engaging. The next question is why isn't a brand new heavy duty clutch engaging. If you hose the rad down is cools off quick, if that adds any insight. Thoughts? Thanks for any help guys

[Gjac]

Did that shop turn your fan blade around yet?

[dougrainer]

Just to confirm what you stated. You state pushing air out. Does that mean the fan is blowing air out the front of the Radiator? If so, THAT is your problem. The air flow comes from the outside front of the Motorhome and is rammed thru by air at 60 mph. The Fan blade PULLS air from the outside in towards the radiator and over the engine block to the rear. If the Fan blade is going the wrong way, there is NO WAY you will get any air THRU the radiator to remove heat from the coolant. Especially at road speeds. The Fan clutch when the temp reaches its preset LOCKS the Fan to spin FASTER to help pull more air thru the radiator. Also, on a Chevy, one bad feature of the fan clutch is, when it does engage, it sounds like your Transmission just down shifted. Doug

[Gjac]

ThorValhallan wrote:
Yep Gjac, we just did a sheet of paper test to confirm. It is pushing air out of the radiator. We're going to call the shop here in a minute to confirm the P/N on the water pump, but I'm betting this was the original issue. I'll update later when everything else has been sorted. I also still want to confirm the initial timing after this is all done, because lord only knows the last time that was checked.

Yes, it sure looks like it. As far as timing goes 454's run much better when you advance the timing some I run mine at 9 degrees BTDC. Some even go up to 12. You will get a performance improvement when you do. I would also check your radiator with your IR gun in a 4 in grid pattern from the top inlet to the bottom outlet and write the temp readings down. You should see an even temperature drop across the whole radiator. Pay particular attention to the center for cold spots which would indicate a blockage. From inlet to outlet you should see a temperature drop of at least 50 degrees if you have a functioning radiator. Also shoot the thermostat housing to see if the temp reading corresponds somewhat to you dash gage reading. Hope this helps.

[Gjac]

I think the fan blade install is your problem. Not familiar with Haydon fan clutches, it should have come on when the engine overheated. Try to spin it, it should not spin freely by hand when cold, maybe 1/2 revolution.

[ThorValhallan]

Yep Gjac, we just did a sheet of paper test to confirm. It is pushing air out of the radiator. That explains why it was running cooler yesterday, I had the doghouse cover off the whole way home watching things, so it was sucking air in thru the coach. We're going to call the shop here in a minute to confirm the P/N on the water pump, but I'm betting this was the original issue. I'll update later when everything else has been sorted. I also still want to confirm the initial timing after this is all done, because lord only knows the last time that was checked.

[Gjac]

When you say the fan spins to the left I assume you mean CCW as you look forward out the front window is that correct? If so the blades look backwards pushing the air forward instead of pulling the air through the radiator.

[Gjac]

Did you check the water pump yet?

[ThorValhallan]

dougrainer,

Thanks for the tstat tip, although I believe it's working correctly. I see the temp needle bumping around when the tstat should be opening.

Talking about the orientation of the fan got me thinking, so I went out to check. Here's a photo of how it looks, disregard the shiny spot. That's just where I laid a piece of reflective tape for my laser tach. For reference, when you crank the engine the fan rotates to the left. Correct me if I'm wrong, but shouldn't the sweep of the fan follow the rotational direction of the fan? Would this not be trying to push air out of the radiator in it's current orientation?

[dougrainer]

I would doublecheck the Tstat or even make sure a tstat is installed.
An OPEN all the time tstat or especially if NO TSTAT will cause the coolant to flow to fast thru the radiator and cause overheating since the fluid goes so fast the heat cannot be removed. Doug

[ThorValhallan]

Ok well, after some more trouble shooting and just watching the engine run I have a little more information. The top and bottom radiator hoses are super soft, but neither of them seem to be collapsing under load. I am going to recommend to the shop that they try a severe duty fan clutch. I believe the Hayden P/N was 2797. What's your guys' experience with Hayden? I had read they're effectively identical to the ACDelco that was OEM on it. I did check the temperature of the back of the clutch with an IR gun, and it was reading around 170-175 but no engagement.

The shroud is in rough shape, I bet it's the original plastic shroud and it's cracked and come apart in several places. As a temporary fix and just to see what would happen I got it set up roughly where it should be (the right side of the shroud was standing away from the radiator an inch or two) and covered the big gaps with some aluminum tape. That seems to have fixed the idle overheat, at least in the cool weather. I let it idle for about 30 minutes yesterday and it seemed fine.

The sticker on the new fan is for a Dorman 621-108. It is a metal fan, looks like the OEM. Only thing is I'm unsure of the orientation of the original fan. It's not backwards, but if it's spinning the wrong way that's effectively the same thing.

Lwiddis,

Yea, I'm going to pick up a timing light and check the timing. That was one thing I had considered. Stock initial is 4* BTDC right?

pianotuna,

Do you happen to remember what manufacturer the fan was from? Or maybe a URL to that thread? If you can't find it no worries, and thanks for the tip

Gjac,

Good point, they had it sent somewhere to have that done. I'll double check that they physically cleaned the rad out. I checked the rad with my IR gun yesterday and the temps seemed fairly uniform

BluegrassBill,

Yea, that's what we're thinking next. It is a steel blade. I'm going to shoot them the Hayden P/N for a severe duty clutch

DougE,

Thanks for the tip about the clutch before install. Would a Hayden be acceptable re the above?

MexicoWanderer,

Thanks for the anecdotes, I'll keep them in mind. Especially driving the truck with no fan as a possible troubleshooting step. Although I'd prefer to avoid that if we can.

[MEXICOWANDERER]

I had to REMOVE the fan on a Dodge then attempt to drive it at 50 mph right away to isolate stuff. The 440L3 immediately dropped from 260F to 150F.

Just for note:
Behind one of those spinning giant air turbine windmills a 40 mph wind calms to the point where a flicked butane cigarette lighter burns with a steady flame. This is just how much "spinning blades" can block airflow.

I have a piece of snot 25-year-old low-miles K car. It was prone to drive hot. I replaced the worn out electric fan motor after 80,000 miles with an OEM used one. Then after a year I got nervous and replaced the one with a 4-seasons electric motor that was noticeably heavier. The man who did the work and I agreed that the new motor spun the fan noticeably faster because the breeze underhood seemed to be stronger. It was a subtle increase though.

Driving the vehicle the actual temperature difference is dramatic. Chrysler decided that a ONE ROW radiator was enough with no possible substitutions. So the fan is VITAL. Only driving 35-50 mph on a mild or cooler day will keep the engine from boiling over without a fan. That all so subtle airflow increase decreased engine coolant temperature by twenty to thirty degrees on a warm day. Since I had purchased the car when it had 18,000 miles on the odometer, and it had the overheating tendency then, it eliminates the idea of age or maintenance influencing things. By the way HOT means boiling over with engine knocking noises when shut off.

The Dodge owner became enraged at the hydraulic fan malfunction. So he eliminated it. He later reported no decrease in fuel mileage. What an expensive odyssey.

Quicksilver has a hydraulic driven Horton 7 bladed fan, a radiator 30% larger in area. Twice the tube count per inch, half again as many fins per inch and a 3 row tube to 5 rows tubes radiator. It survived a 12-hour day flat towing a loaded 1 ton pickup truck in temperatures to 122F. I didn't fare nearly as well. I had traded an LA radiator shop for repairing a Cummins Onan 700 Kw generator.

[DougE]

This has been an issue for decades. Since you don't hear the fan clutch pulling in:
Use only a factory fan clutch. Set it in the vertical position for 24 hours before installing.
Check your radiator with a Harbor Freight infrared heat gun to see if the temperature differences across the radiator core make sense.

[Gjac]

When you say the shop rodded out your radiator are you sure they actually mechanically cleaned out the tubes or just ran a chemical flush through it? You are smart to check the water pump part number first, that will tell you if they put a reverse rotation one in.

[pianotuna]

This has come up before. In the other thread the wrong fan was installed iirc. It is the same part number--but there is more than one model.