RangeRovers.net Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Ok, I would really appreciate some input as I'm pretty stumped on this one. What else am I missing???? or can check.
I am getting an overheat and it takes a bit of time but it will run idle at take longer to overheat. It really heats up under load/driving.

I have down a block test, liquid stays blue. No leaks anywhere.
Ive burped/bleed as much air out of the main coolant stem that goes to the heater hoses, I fixed a kink in a heater hose as I thought that might have been it. The suction hose at the bottom of the radiator does not collapse so I dont think air is an issue.
I have blown out the heat exchanger for the heater so it is clear.
Pulled out the Thermostat because the flow from the pump seemed low. So I am presently running no thermostat.
Replaced the Water Pump now flow coming thru upper and lower hose if squeeze are more firm but still getting hot. Top seems hotter than bottom.
I have not changed the radiator. I basically pulled out the 4.6 and dropped in the 4.2. The 4.6 blew a head gasket but was not overheating.
I guess replace the radiator is next.
I'm running a 12 electric fan. Its presently running constant and still overheating....
I can feel the air being pulled thru the radiator so I know that the air flow is good.

This was a transplant. Is there anything from the 14CUX that could be haywire that would cause an overheat? I have not wired in the fault indicator. So i have no way to check codes.

The only thing that I can think of is to get a new maybe bigger radiator for it.
The cooling system builds up pressure so I am pretty sure its not a radiator cap issue.

Im thinking maybe the Radiator since it IS the last thing that really could be restricting flow. If the temperature switch is bad would that cause an overheat per 14CUX?

Any input or ideas on where to focus or look would be greatly appreciated.

Thank you
Rodge
 

·
Registered
1970-1995 Range Rover Classic
Joined
·
64 Posts
I found the radiator out by taking the viscous fan off and letting it run, the end caps of the radiator got very toasty but I could place my hand on the middle of the radiator and it was cold. New rad and it got hot uniformly all over and made me think I shouldn't have overhauled and top hat-ed my 3.9. oops. Was well overdue some love in any event.

Sent from my LG-H930DS using Tapatalk
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
Thanks for the input I know a lot of guys have the fancy laser thermometers Im too cheap for that .. but your solution is a great idea. I'll pull the electric fan off and give it feel.... :)
 

·
Registered
1970-1995 Range Rover Classic
Joined
·
252 Posts
I would try a twin fan set up (one set at 180F and the other at 210F) you can play with the temps. Also, have the radiator checked while it is out.

Cheaper option - swap to a viscous set up if you have the components as a test.
 

·
Registered
1989 Range Rover Classic
Joined
·
213 Posts
I'd second the laser thermometer, they're literally $15 from amazon. It also might be worth having the radiator rodded out or replacing it, being a disco I imagine it's the 2 core aluminum rad? Nissens makes pretty decent replacements, they're not very pricey either.

In general though, a single 12" electric fan is not enough. I have two 12" puller fans on my classic, plus two 10" pusher fans as backup (replacing the condenser fans). Unless you live somewhere where the temperature never gets above 60 degrees, a single 12" just isn't going to cut it, especially at idle.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #6
Well, I peeled the electric fan away, and ran it. I just am not entirely convinced its the radiator. The end caps do seem somewhat more hot than the rest of the radiator. However, the old 4.6 was running fine and not overheating at all which leads me to think the radiator is ok and when running hands over the entire radiator the entire radiator gets hot and its fairly uniform. Not cold anywhere. So Im thinking Ive got a potential restriction someplace else. Which I think about the only last place I can check for potential restriction is the connector on the intake manifold that has a small rubber heater hose that comes back from one of the heat exchanger pipes. I don't think the other pipe is restricted from the pump because both heater pipes are hot so maybe that intake coolant hose might be corroded or blocked. The motor had sat for a while on a pallet so anything is possible. It runs fine just this darned overheating is driving me crazy.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #7
All, I swapped the Viscous out because it was overheating as well under the stock setup. I figured I would try the 12'' electric funning constantly as a part of troubleshooting that's why I also removed the in-nerds of the thermostat as well and replaced the pump to ensure full flow. All belts are nice and tight. Still no dice. I'll have to order one of those thermometers if they are that cheap would be a nice little extra tool to have around! It takes longer to get hot at idle and if I drive it. The increased airflow is still not bringing the temps down and that even with a 12" running constant. So Im still kind of thinking restriction somewhere but not convinced just yet its the radiator. Timing, seems fine. I think the temperature switch is bad with a ground somewhere because when I wired the relay the fan just immediately comes on with the key on but that shouldnt have anything to do with the overheating. Thanks all!
 

·
Registered
1970-1995 Range Rover Classic
Joined
·
252 Posts
When the VC fan setup was failing on my 95'RRC it would only run warm under a load (hills, etc.) under idle it was fine.

Still seems like air volume.

I have a spare radiator you are welcome to try if you want to go through the trouble - located on the east coast 30004.
 

·
Registered
Joined
·
456 Posts
For analysis, you need to check with the new thermometer the top hose temperature versus the the bottom hose to consider the temperature drop across the radiator.

If someone else has figures for the same to compare it would give you more insight.

Cabin heater matrix shouldn't be affecting engine temperature, I'd discount that as a cause.

Check thermostat in boiled water to see if it opens as temperature is raised. Should run with one fitted as it helps to hold pressure within the block and scavenge heat more effectively from mechanical interaction with the water jackets.

Have you double checked the routing and connections of any small "bleed " hoses from top of rad, engine and reservoir header? They are important in orientation to prevent air lock and stay fully bled out in operation.

If you've not got sufficient temperature drop across rad (the hoses check above) then it's either water flow or air volume. If it's just sending coolant back over temperature, then it'll quickly accumulate and overrun the system capacity.
 

·
Registered
1989 Range Rover Classic
Joined
·
213 Posts
I know you said you bled the hell out of it, but I hate to say this still sounds like an air bubble. That would explain what I am assuming is poor water flow. If it overheats on level ground at speed, it's not an airflow issue (although I still recommend at least two 12" fans regardless). If its a water flow issue, it's either the water pump (which you said was new), the thermostat stuck closed (you don't have one currently), severely clogged water galleries (possible?), or an air bubble. I had one hell of a time bleeding my rover, it's not an easy job. I ended up disconnecting the heater hoses and rigging both vertically, one with a long hose going into it and a funnel on top filled with coolant, and let it sit overnight. That got the big bubble out, but it continued to burp smaller bubbles (and requiring more coolant) for almost a week afterwards.


Side thought, and this is just a wild sanity check; are you sure you ran the serpentine belt the correct way? If not, the water pump would be spinning backwards.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #11
All, ok I think I solved a significant part of the problem with the simplest of things. From some of your recommendations I went back and double checked all the hoses and clamps to make sure everything was routed correctly, remembering that water pumps cavitate sucking air. Sure enough, I found that I had not tightened down the clamp that goes on the small hose that provides deicing to the intake. Hose wasn't lose enough to leak fluid because being fairly snug but I must have forgot to tighten the hose clamp it was completely loose and I'm sure it was sucking air and the new pump wasn't getting up to full flow. The other end of that small hose runs over to the bottom of the expansion tank. Once I tightened it down and started it I noticed it immediately seems to have stabilized the overheating.

Tomorrow, I'll put a working thermostat back into it and trouble shoot the temperature switch on the elbow as well so I can get the fan to cycle on and off correctly. However for right now having the fan run 100% is fine for a few days until I get a new switch.

I do think I will at some point want to upgrade to the dual fan as some of you suggested. I'll have to see what I can find by way of OEM at a salvage yard. Either way I am pretty excited about the swap. I was not even going to attempt a rebuild of the 4.6. 4.0/4.6 just not an easy engine to work on I hate that whole set up. These 3.9/4.2 with the distributor, everything is just SOOOOO much more easy to work on. Kind of like the best of being old school cool with a flair of high tech with the hybrid 14cux fuel injection.

Thanks all for your help. I'll update if anything changes.
 

·
Registered
Joined
·
456 Posts
Sounds like you're on the right track at least.

The thermostat will assist in preventing pump cavitation too. When run without in competition applications they often use a venturi in the engine exit hose to cooling for that purpose. An important part of most cooling system strategy to have something in place.

But I'd agree with your initial finding, they will suck in air from any small leak on feed side of pump. It's this effect that should just pull down from header tank to keep replenished from competent liquid supply that prevents most of air locks on any car systems.
 

·
Registered
1989 Range Rover Classic
Joined
·
213 Posts

Attachments

·
Registered
1989 Range Rover Classic
Joined
·
213 Posts
I was paranoid with overheating since we go camping in the desert a lot (towing a small trailer), so there's those two pullers, two 10" SPAL pushers in front, and then an auxiliary oil cooler with two 6" pullers on it. Maybe overkill, but aluminum motors don't like heat!
 

·
Registered
1970-1995 Range Rover Classic
Joined
·
359 Posts
You can transplant all the distributor drive gear onto a 4.6, no point in throwing it away if it’s a good engine.
 
1 - 16 of 16 Posts
Top