!&*@! ..... still overheating! - Defender Source
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  #1  
Old June 6th, 2005, 05:20 PM
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!&*@! ..... still overheating!

I've got a recurring overheating problem that I don't know where else to go with.

Here is the symptom: when sitting still, or in extended stop-go traffic, the needle slowly climbs until it reaches the 'red zone'. I've had to pull over and let it sit to cool off several times to get around this.

* I've replaced mechanical clutch fan with dual electrics - helped, and delayed the overheating, but it still occurs.

* I put in a new thermostat, no difference

* I put in a lower temperature electric fan switch, nada

* I put in a new, custom 4-core monster radiator, and it still overheats!!

When the car is driven down the road, I can go all day without a problem so long as it's moving. This implies that either 1) not enough air is getting through the radiator (which I find hard to believe), or 2) the cooling effect from the moving vehicle keeps the engine cool because the coolant from the radiator is not. If it's #2, what's the problem? Any other possibilities?

1) Could the water pump somehow not be pushing enough coolant? How? The belt shows no signs of slipping, doesn't appear to slip watching it and there is no noise...

2) Could the internal passages be blocked somewhere and coolant isn't flowing correctly? I did not see big signs of corrosion when I changed the thermostat.

3) Could the temp sending unit be insane? I doubt it, as once I let it go until the engine light flickered as a test.

I'm not sure what to do next on this issue...
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  #2  
Old June 6th, 2005, 06:48 PM
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Since a real temp guage is so cheap (VDO vision about 25 dollars- fits perfectly too) I would get one of those, along with a new sender, and actually measure the temperature. One odd problem I have in my D90 is that extra electrical accessories being switched on makes the temp read high (I have verified there is no actual temp change) maybe you have that problem too.

There is some chance that you have an air pocket, but since it sounds like you've flushed the coolant several times this seems unlikely, unless there is a systematic error in your fill and bleed procedure.
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  #3  
Old June 6th, 2005, 06:49 PM
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head gaskets?
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  #4  
Old June 6th, 2005, 08:14 PM
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OK letís try ruling some stuff out.

1 I hate to think it's a head gasket but the test is simple, go to Napa and buy a (I think) hydrocarbon test kit. You test the coolant to see if there are exhaust gas vapors in it.

2. Next time the temp starts to climb turn on the heater full blast set to hottest. How hot is the air coming out? Does it get hotter as the temp gauge starts to rise?

3. Feel the radiator up (get ready to burn your hand) is there any hot or cold spots indicating that it has poor flow or blockage?

4. Is the system pressurized? Next time it is warming up squeeze the top radiator hose when running (gonna burn your hand again) is it hard or does it squeeze the same as when the engine is cool and not running?

5. Do you have AC? The AC radiator could be clogged up with mud restricting air flow through the big radiator.

6. How old or how many miles on that water pump? Normally when they go they start to weep coolant out the front behind the pulley.

7. if you don't get a new temp gauge check yours against a good one, you only need to pull the sender out of the block, ground the case of it then stick it in a pot of hot water with a normal thermometer and compare.

Test in whatever order you like I just numbered them for to make replying easier
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  #5  
Old June 6th, 2005, 08:39 PM
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JimC,
I think I have in fact noticed some suspicious behavior in the gauge with respect to the electical system load.. very subtle, but I'm pretty sure I've noticed it. Changing the gauge isn't hard - and I've already a VDO tach in that position, probably not a bad option.

I'll double-check the bleeding procedures for this engine (I have the manual) to make sure I didn't screw it up.

flipped,
I hope not, but...


Mike,
1) I've never heard of a hydrocarbon test kit - I'll have to check that. If the head gasket is leaking, a symptom could be low pressurization on the system because it's leaking out the jacket and into the exhaust, right? Or, is the pressure such that it wouldn't leak that direction? I never notice a low coolant level -- it doesn't seem to lose fluid (at any kind of noticable rate). How would leaking head gasket lead to overheating (when I don't have any fluid loss I can notice)?

2) I did the heater blast out of necessity to try to avoid the overheating situation. I didn't pay attention to temp change, though.. in fact, I was near passing-out from the heat. I'll try that the next time I'm stuck in traffic (it's LA, shouldn't take too long).

3) I hope this isn't the case - it's a brand new radiator core! It's hard to check with the fans installed - I suppose I could go in from the front and take off the grill.

4) I'll check this - I can't remember if it is or not, come to think of it.

5) No AC, but I'd like to add it. The big radiator was partially to help accommodate that.

6) As far as I know, it's factory 92K miles. No sign of leakage out the weep hole...but, would this cause overheating? It's pretty much impossible for that impeller to become somehow 'decoupled' from the pulley drive, isn't it?

7) I would already have had a new sender in there, but no one carries it. Appears to be a dealer-item, etc. In fact, I was lucky I could re-use my thermostat housing gasket - no one had that, either.

I hope it's not a head gasket....
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  #6  
Old June 6th, 2005, 08:51 PM
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Is your "Change Engine" light on?

Tdi wont overheat.
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Old June 6th, 2005, 09:04 PM
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2 things that headgasket can do. Coolant leaks out or into the engine and out the exhaust, or exhaust gets in, pressurizess the systems or creats an air bubble and blocks coolant flow, but most of the time when that happens it also pushes coolant out the overflow tank also.

Allot of things can cause no pressure build up, then coolant/water has a lower boiling point, but normaly when this happens the the boiling causes an overflow at the expansion tank.

The block could also be blocked up some? Causing bad flow, how much of a differance in temp is there between the upper and lower radiator hose?
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  #8  
Old June 6th, 2005, 11:22 PM
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Ok, here's a few thoughts.

1. ) You said you went with a 4-core radiator? Might be that the additional core is limiting the airflow enough to make the fans insufficient for the application. Especially if you have a denser pattern to the radiator. Which fans do you have? (also, V-belts or Serpentine Belt engine?)

2. ) Somehow getting insufficient voltage/amperage to the fans, which is slowing them down? Are you sure they are coming on properly, spinning the right way, and not blocked somehow? Are they wired straight to the battery with big enough wiring?

3.) Check the ignition timing. Also, might not be a bad idea to confirm the timing marks on the balancer match reality. Bad timing can/will make the engine overheat.

4.) Maybe some kind of obstruction in the system, which is overcome by the higher pressure from the waterpump at higher RPM? I have seen worn/busted impellers in cars before.

That's all I can think of at the moment for things that might be problems.

-Hans
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  #9  
Old June 7th, 2005, 12:32 AM
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Jason,
There have been reports in the UK of some Non-Genuine waterpumps causing wierd overheating problems...seems the impeller is manufactured slightly differently and is not as efficient and doesn't flow enough. I have not personally run into this, but something to think about as you narrow down the possibilities.
Rob
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  #10  
Old June 7th, 2005, 12:51 AM
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The block test kit from Napa is #700-1006. I have used it and it works well. I now consider it a valuable tool to have around. It will detect exhaust in the coolant, but this does not mean it is a head gasket. It could also be a porous block or slipped liner that will also give the positive test. I hope it is none of these. Since you have no problems at speed, I would take a close look at flow and water pump. To check for fluid clogs in the radiator, I used a IR heat tester and checked the different rows of my radiator to see if there was much variation--this will also give your gauge a second opinion. If you are not expending coolant, you may not even have a problem. The IR thermometer is also useful in checking the exhaust temps to see if one of the cylinders is not firing...this would not be one of your problems, but just another use for the IR.
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  #11  
Old June 7th, 2005, 12:54 AM
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An outside chance but worth asking...is it possible you reversed the polarity on the fan wiring causing them to pull hot air through the radiator?

TG
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  #12  
Old June 7th, 2005, 01:29 PM
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The fans are wired to the positive side of the alternator, which goes straight to the battery. They are pulling the correct direction and seem to flow alot of air (they are Hayden - typical auto parts house fans with swept blades, not straight ones). When they kick on at idle, you can notice a slight dimming of the lights - I never notice this at speed, though. The overheating was must worse when the old mechanical clutch fan was installed - so, I think they are an improvement treating a symptom, but not a solution. I have the multi-belt setup, not the serpentine.

This problem existed before the new radiator - I had hoped the radiator would solve this problem and ready me for an A/C install with the extra cooling capacity.

The system does not seem to be pressurizing, I can still squeeze the top radiator hose when she's hot - this is a problem. The radiator cap seems to seal and doesn't look worn, but I'll replace it (got home too late to hit the auto parts store last night) and also check the hoses between the remote radiator resevoir and the radiator for a faulty seal. There is no sign of a leak, no sign of overflow/backflow of coolant. Maybe I'll get lucky and it's a radiator cap, but I don't count on my luck

I looked through my Genuine Land Rover service manual, and could not find any mention of a special fluid bleeding procedure. I in fact followed the pretty simple process outlined in the book to drain/refill the system. Is there something else I should be doing to bleed it properly?

As for head gasket - there is no sign of strange color in the exhaust or discoloration in the oil (that milky-color which is a sign of coolant-oil mixing), and no backflow of the system. Maybe the lack of pressure is simply a radiator cap? I'll find out tonight.

Thanks for all the ideas --
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  #13  
Old June 8th, 2005, 10:01 AM
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That is a bad way to wire the fan positive power. It is a bad practice to tap power so close to the alternator. It can cause alternator problems as well as power surges to the fans which can cause the fans problems. Go to the underhood fuse box or battery directly with inline fuse. I understand it was easier to wire this way but it will cause problems. Good luck on your overheating issue.

JP
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  #14  
Old June 8th, 2005, 01:34 PM
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I've had this problem on other cars (not the '90). Cause was a dying water pump.

Can you get the temp to go down by revving the engine?
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Old June 8th, 2005, 03:38 PM
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Quote:
Originally Posted by pendy
That is a bad way to wire the fan positive power. It is a bad practice to tap power so close to the alternator. It can cause alternator problems as well as power surges to the fans which can cause the fans problems. Go to the underhood fuse box or battery directly with inline fuse. I understand it was easier to wire this way but it will cause problems. Good luck on your overheating issue.

JP
Jim,
I'm curious about why? If I run a wire (which has an inline fuse, by the way) to the positive terminal of the batter, the only difference is that I have slightly more resistance (I would have to say a very small amount more) in the form of more copper wire between me and the alternator - it's effectively the same circuit. I'm not bypassing a voltage regulator, as that's built into the alternator these days (not like on my old '73 Dodge Charger, which had an external one). I'm curious why this is different/bad. It is of course easier, but I didn't wire it that way because it was easier, but because it was electrically the same.

Barry,
Revving the engine just makes it hotter I think my first problem is to solve the lack of pressurization of the system... I hope that's not a head gasket. I was 0 for 4 in trying to find a radiator cap at the auto parts chains yesterday.... might have to go to a dealer??? Geesh.
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Old June 8th, 2005, 04:34 PM
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I got a cap from Autozone it was 16 psi not 15 like the original but I figured close enough. As far as the wiring goes, the alt generates allot of ripple or Alternating current, the battery acts like a capacitor and absorbers what the diodes in the alt don't take care of. So you get a very clean signal from the battery while you would get a dirty signal from the alt.

Some reading regarding the alternator noise

http://www.sacskyranch.com/altnoise.htm

http://ccs.exl.info/noise.html

How do I know about the noise? Well I work in an electromagnetic interference testing lab, and this stuff is what I measure, and induce onto equipment all the time. Believe it or not most auto manufactures have standards as too how much noise something is allowed to produce and how much it should be able to handle. But it is always better to use clean power rather then subject something unnecessarily.

OK back to overheating!
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  #17  
Old June 9th, 2005, 11:07 AM
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On the wiring for the fans. Do you notice the lights brighten as you rev the engine. This false load on the alternator from the lights that is not using battery storage correctly is the problem.

You may have a ground issue on your tempurature gauge. Run a new ground wire from the engine block to the bulkhead. Also check the connection at the transfer case and frame for the negative cable from the battery.

good luck
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Old June 9th, 2005, 06:22 PM
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The lights don't seem to brighen at all when the engine is revved - they only dim very slightly when the fans kick on.

So, from what I'm understanding here, the point of connection - even though it's a common circuit - could cause some problem with the fans due to induced AC current. I understand the battery as the AC sink, but a little unsure why the connection makes a difference... theoretically, except for a very small amount of resistance in the wire between the alternator and the battery, the circuit is the same whether it's connected closer to the alternator, or on the battery post as there is nothing between the alternator and the battery post - it's a direct run.

In all the circuits classes and simulations I've ever done, the wires are basically considered to be of 'zero' resistance because they are so very much lower in resistance than anything else in the circuit. However, in this case, the *actual* circuit would be rather than a common connection point (battery, alternator, fan power feed, other power feeds), the circuit woudl be (alternator, fan power feed) <very small resistor> (battery, other power feeds).

Or, is the problem that because the power feed for the fan is simply NEAR the rotating alternator stator (when connected as I have it) that the induced AC current is created in the fan power feed wire? That makes some kind of sense to me, and then makes a good case to keep the alternator away from other power wires which could be subject to the induced current....
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Old June 9th, 2005, 09:44 PM
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Jason, you hit it right on the head in the last sentance there. It's not a matter of additional resistance at the alternator connection, but you are getting a very dirty power flow due to the noise induced by the alternator being so close. The end result isn't more resistance, but an inconsistant current.

Going straight to the battery will give you a much cleaner power source, which will definitely make a difference in the life of the fans.

-Hans
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Old August 18th, 2005, 05:56 PM
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OK, so after alot of horsing around I still can't get my cooling system to pressurize and still experience overheating when in long periods of stop-go traffic (in LA, this is hard to avoid perpetually). I also still can't *see* obvious sources of coolant leakage (whether externally, or into the combustion chamber or oil), but a mechanic told me when I bought this vehicle that I'd need a head gasket eventually (I should have asked for more detail, but I didn't) and he may have mentioned potential overheating....I'm foggy on the conversation.

So, I picked up a head set from British Pacific. Before I get this installed, is there any chance I have the cooling system improperly 'bled'? People have said "make sure it's properly bled" - however, my manual has a rather implistic method to refil the radiator which does not sound 'special' in any way. If there is too much air in the system then perhaps I'm not in need of the (labor-expensive) head gasket replacement.

Maybe I'm just trying to avoid the inevitable, but I would hate to redo the head gasket and STILL have an unpressurizing system (and then overheating).

Another question: what are the odds my head is warped? Is that a common problem, possibly the cause of the leaking I'm told I probably have? Could I just get the heads re-decked/shaved to take care of this when they are off for the gasket replacement? (bonus of slightly more compression?)

I've also picked up a used A/C system and plan to install that soon. Anyone see a problem in wiring the A/C electric pusher fan to come on with the twin pullers?
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