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Discussion Starter #1
I did post this before but the title was misleading and the thread went off on a tangent because of it... I want to repost to be more focused on the engine/cooling rather than the electric fans which I now know are not the issue.

So to recap.. 1998 range Rover 4.6 HSE, 116k miles. Recent new radiator fitted, fan clutch feels ok, and is moving air at idle, and no leaks from waterpump or elsewhere. Heater core is bypassed before we bought the car due to a leak, but thought I would mention it.

What started this was the pressure cap was not screwed down tight or faulty resulting in coolant loss, GF said the temp gauge spiked in traffic here in California. I topped it off, Burped the system I think, yet the temp gauge will still spike almost to the red after 15 mins idling in the garage with ambient temps in the 80'sF. Last time I drove it, the gauge stayed a touch to the warm side of center while on the freeway at 70mph, but spiked again as soon as I slowed down.

Someone suggested I may have a headgasket gone, someone else a dropped liner or a porous block..

If I leave the overflow tank cap off and warm the engine, as soon as the top hose gets warm the coolant seems to expand out of the tank pretty fast and overflows. The top hose does get pretty hard and my testing was stopped for a couple of weeks because the pipe from the top of the engine to the heater sprang a leak and dumped all the coolant out(on examination, I think it was just old).
Also, maybe connected or not, I can hear a slight "chuff" sound from the RH head/exhaust manifold, that I have been unable to locate. I tried to remove the heat shield to locate the noise but one of the bolts holding it on wont come loose.
Yesterday I pulled the spark plugs on the Right bank looking for clues... all looked fine except the rearmost plug that has a brown deposit that the others dont...
Pic.


Can someone help me diagnose or pinpoint the problem?
I have good skills, and have rebuilt 3 engines in the last 2 years as well having a well equiped garage, including a compression and leakdown testers.
I dont want to rip the engine apart for a headgasket only on reassemble to find its the porous block and have to rebuild it again!
 

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Discussion Starter #2
I will have the hose replaced today, and plan to refill the system with plain water for the next stage of testing as I either will be ripping to engine apart or will need to flush the antifreeze out to try some Block sealant.
Anyone had experiences with these if it seems worth a try?
 

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We had a similar problem with my GF's 4.0.
Long story actually (hope you don't mind):
When I bought the car it had a small leak on the LPG vaporiser, my previous GF (driving what was at the time my car) ignored the rising temperature needle 'because she was almost there' and parked it with the overheating warning on. :(
I refilled the coolant, drove it carefully after fixing the leak but experienced some more issues with the temperature rising and coolant disappearing (possibly through the pressure cap). I than put in a new radiator, temperature remained good, even when towing, but I did have to top up the coolant regularly.
Still took it on holiday with a loaded cartrailer attached, and to my big surprise, no coolant disappeared anymore!
The engine got a new cam and chain early this year and was transplanted into a different car. First traffic jam of summer, and temperature started climbing again. :( But no obvious water loss. I then replaced the thermostat (after swapping the viscofan to no avail) and it seems to be OK now. :pray:

Mind you, we only had the problem in very slow traffic, never just idling.
Once the engine could rev to 1500 rpm all was fine. This even worked to keep the temperature well below critical when in traffic, just put the car in N and rev the engine slightly. I know this point to the waterpump, but that's (supposed to be) a new part. My guess is the flow was hindered by the old thermostat, only opening fully when the faster spinning pump exerts more pressure on the system.

Hope this helps!

Filip
 

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Discussion Starter #4
Update.
I drained what was left in the radiator and refilled with clean water. Removed the top hose at the raditor and poured water into the block until it was full. Removed the small hose from the Right side of the radiator that goes to the overflow tank and filled the tank until the water started to overflow from radiator. Started the engine and topped up until water began to flow from that pipe where it enters the overflow tank. At this point I screwed down the cap and let the engine idle, and in 5 mins the hoses were getting warm.
Ambient temp here today is about 85f, and the RR is in the garage in shade with door open. Temp reading are taken with my IR thermometer on the hoses and radiator casing. AC is off.
After idling for 10 mins the temp gauge was reading normal and Radiator top and hoses reading 185/190F. between 10 and 15 mins the gauge began to rise to the end of the "normal" range, and Radiator temp is reading 200/205F.
I found that if I revved the engine to 2000rpm the gauge would drop within 1 min to abou 2/3 hot but not back to normal.
After 20 mins the temp rose to H and the warning lamp came on. Radiator temps were reading 220f, and top hose is pretty firm, but I can squash a little before my fingers feel like they are burning.
Turning AC and headlamps on and off had no effect on the gauge so I think I can rule out electrical issues.
I could see no sign of water being blown out past pressure cap, but area was wet from filling, so maybe I cant see it.
I shut off the engine and am going to let it cool and check water levels again, and top off if I need to
 

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regarding the "chuff":
may be a cracked exhaust manifold. crack is "open" when it's cold, as manifold heats, it expands, the crack closes.
 

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Discussion Starter #6
Yes, it does quiet down when it warms up but its by no means a loud thing.
 

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I's say you have quite an advantage with the IR thermometer. For one, you could verify if the temperature in the radiator is lower at the bottom. Or if there are hotspots.
Since it also seems to be dependant on the engine rpm, I'd look at viscofan, thermostat and water pump.

Hope you find the cause!

Filip
 

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The two rear most cylinders are the worst but not always.

To give you abit more insight into over heating issues dig around my blog and check out pictures in the cooling system report......
 

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Discussion Starter #10
Thanks Viper,
In fact I dd look thru your blog before and absorbed the info.
The rad is new... like maybe 1000 miles, so I see no reason to suspect it.
How do I test the Viscous Coupling?
How do I eliminate the Thermostat from the search for the cause?

Would a Compression test show anything?
 

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KeyRange said:
Thanks Viper,
In fact I dd look thru your blog before and absorbed the info.
The rad is new... like maybe 1000 miles, so I see no reason to suspect it.
How do I test the Viscous Coupling?
How do I eliminate the Thermostat from the search for the cause?

Would a Compression test show anything?
The viscous fan should be seen and heard spinning at approx engine rpm when up to temperature. If it looks OK, try stopping it with a rolled up newspaper or piece of cardboard (be carefull!), if it slows down the coupling is to weak.

I don't think there's an easy and reliable way to test the thermostat, but you can use the IR thermometer to get an idea of the flow through the rad, which is controlled by the thermostat.
 

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Discussion Starter #12
From my research it seems that the Thermostate is in a small plastic casing on the lower right side of the radiator... with my IR I get a pretty consistance temp reading everywhere.
The fan/clutch does move air, and When I rev the engine to 2000rpm the air quantity and noise level rise for maybe 10 seconds then you hear the fan begin to relax, and get quieter... is that what it should do?
When cool and engine off, I can turn it by hand, but there is some resistance.
As for stopping it... how much pressure with a newspaper or the like is enough?

I do have an admission of stupidity...
A couple of days ago after I posted the warmup and temps update, i left it to cool down..
Maybe 30/45 mins later I went back to check it and noticed a slight hissing noise from the pressure cap on the overflow tank.
Without thinking about it properly I thought it had cooled and I was hearing the fluid being drawn back in, and as I was overkeen to get it figured out and top up/burp the system I began to unscrew the cap....
The cap blew off suddenly in my hand scalding my hand, and rewarding me with a trip to the Dr.
After 3 days later it is much better, but I was lucky on 2 fronts... One, I held the cap down instinctivly and saved getting the scalding water in my face, and two, a life of manual labor gave me tough hands, so the worst of the burn was between my fingers and forearm which is an interesting shade of purple right now! The Doctor who examined me today says he is amazed that I suffered no worse and ther is no blistering.
People reading this thread now and maybe later in a search, need to know that it was so painful despite it being bathed in cool water within 15 sec, I needed a trip to Urgent Care, Bandages, burn cream, Antibiotics, and Vicodin. I would have needed a Tetinus jab too if I had not had one a couple of years ago.
The lesson is that the screw on Range Rover cap goes from sealed to "fly-of- in-your-hand" without a warning hiss, and the is no safety detent like on a lot of cars....
BE CAREFUL!
 

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Discussion Starter #13
With the statement above in mind...
Do i have a overpressurized and overheated cooling system due to a engine problem?
 

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KeyRange said:
I did post this before but the title was misleading and the thread went off on a tangent because of it... I want to repost to be more focused on the engine/cooling rather than the electric fans which I now know are not the issue.

So to recap.. 1998 range Rover 4.6 HSE, 116k miles. Recent new radiator fitted, fan clutch feels ok, and is moving air at idle, and no leaks from waterpump or elsewhere. Heater core is bypassed before we bought the car due to a leak, but thought I would mention it.

What started this was the pressure cap was not screwed down tight or faulty resulting in coolant loss, GF said the temp gauge spiked in traffic here in California. I topped it off, Burped the system I think, yet the temp gauge will still spike almost to the red after 15 mins idling in the garage with ambient temps in the 80'sF. Last time I drove it, the gauge stayed a touch to the warm side of center while on the freeway at 70mph, but spiked again as soon as I slowed down.

Someone suggested I may have a headgasket gone, someone else a dropped liner or a porous block..

If I leave the overflow tank cap off and warm the engine, as soon as the top hose gets warm the coolant seems to expand out of the tank pretty fast and overflows. The top hose does get pretty hard and my testing was stopped for a couple of weeks because the pipe from the top of the engine to the heater sprang a leak and dumped all the coolant out(on examination, I think it was just old).
Also, maybe connected or not, I can hear a slight "chuff" sound from the RH head/exhaust manifold, that I have been unable to locate. I tried to remove the heat shield to locate the noise but one of the bolts holding it on wont come loose.
Yesterday I pulled the spark plugs on the Right bank looking for clues... all looked fine except the rearmost plug that has a brown deposit that the others dont...
Pic.


Can someone help me diagnose or pinpoint the problem?
I have good skills, and have rebuilt 3 engines in the last 2 years as well having a well equiped garage, including a compression and leakdown testers.
I dont want to rip the engine apart for a headgasket only on reassemble to find its the porous block and have to rebuild it again!
Sorry 2 hear abt ur awful experience.ok i think ur having an airlock in ur system.if u don't have oil in water or water in oil so exclude the h/g.if u hear a piston slap and the plugs look like steam cleaned than u have a slipped liner.try the following coz it cured my pro but do it if ur sure that there is no leaks in the hoses.get a garden hose with a continuous water flow.when engine is cold in the morning,open ur expansion cap,remove the small bleed pipe from radiator(don't brake the nipple) then blow through it to make sure it's clear.with engine off pour water from ur garden hose into exp tank,keep it 4 a couple of minutes,water should be coming out of the rad nipple,now try 2 attach the garden hose inside the exp tank and run 2 start the enine.control the water flow from the garden hose into the exp tank in a way to keep it balanced with the water thrown from rad,continu doing that,if air lock is present u'll c the rad nipple spitting the air w the water.put ur finger in the water coming from rad nipple when u feel it is hot and no more air coming from nipple,attach the bleep pipe to rad and remove the garden hose.now look inside the exp tank .u must 2 water driping from the small hole located at the edge of exp tank from inside,if it isn't dripping than the hole is clogged (it is better 2 b prepared w a fine object to poke the tiny hole,before starting this mission).if water is coming from hole close the exp tank.all this procedure must take from 5 to 10 min.DO NOT LET THE TEMP GAUGE REACH HALF BEFORE CLOSING THE EXP TANK OTHERWISE THE EXP TANK WILL FLOW.
 

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Discussion Starter #15
Ok, will try that...
I know the overflow pipe to the tank is clear because I see water coming from it and dropping into the tank when I filled it before.
Will try this and report back soon.
No obvious steam from the exhaust or into the oil...
 

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Discussion Starter #16
I think I got it!
Checked the fan with the tightly rolled newspaper... not for the faint of heart.... it chomped the newspaper before I could slow it and sprayed me with the confetti!
So, I did the fill as was suggested above, and had water flowing freely from the radiator nipple.. all good... filled until the temp reached the middle of the gauge, kept a flow of water going into the overflow and squeezed the top hose to massage the air out. I could see water flowing from the hole in the neck of the overflow consistantly so as the coolant expanded, I put the cap on and took it for a short drive.
Within 1/2 mile it was beginning to get hot, so I returned home.
It was reading at the upper quarter of the gauge when I stopped.

I checked the radiator temp with my IR, and here is where it got interesting..
Top of Rad is too hot to touch.. reading was approx 205F, as was the top hose and heater hose pipes and overflow.
Pipes on the upper side of the black plastic housing that I think is the thermostat were also 200F+, but the short larger diameter hose that comes from the bottom of the housing to the radiator was cool to the touch and reads 105degF... as did the bottom of the radiator!
So... Does that mean its the Thermostat that has failed in the closed position????? 8-0=
 

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KeyRange said:
I think I got it!
Checked the fan with the tightly rolled newspaper... not for the faint of heart.... it chomped the newspaper before I could slow it and sprayed me with the confetti!
So, I did the fill as was suggested above, and had water flowing freely from the radiator nipple.. all good... filled until the temp reached the middle of the gauge, kept a flow of water going into the overflow and squeezed the top hose to massage the air out. I could see water flowing from the hole in the neck of the overflow consistantly so as the coolant expanded, I put the cap on and took it for a short drive.
Within 1/2 mile it was beginning to get hot, so I returned home.
It was reading at the upper quarter of the gauge when I stopped.

I checked the radiator temp with my IR, and here is where it got interesting..
Top of Rad is too hot to touch.. reading was approx 205F, as was the top hose and heater hose pipes and overflow.
Pipes on the upper side of the black plastic housing that I think is the thermostat were also 200F+, but the short larger diameter hose that comes from the bottom of the housing to the radiator was cool to the touch and reads 105degF... as did the bottom of the radiator!
So... Does that mean its the Thermostat that has failed in the closed position????? 8-0=
It is most likely 2 b the tstat,as an indication of a cold bottom hose and cold bottom rad,it makes sense water is not circulating through the rad.replace it.don't forget after replacing bleed again.good luck
 

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Discussion Starter #18
Ok, ordered one...
I am so excited!
I was thinking that this was going to be something time consuming and very expensive!
Fingers crossed!
 

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I have to tell you viperover, if you haven't heard this lately your Blog is incredible!
Thank You :clap: :clap: :clap:

Scotty
 

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Discussion Starter #20
Scotty said:
I have to tell you viperover, if you haven't heard this lately your Blog is incredible!
Thank You :clap: :clap: :clap:

Scotty
Agreed.
Hope to have the Thermostat by the end of the week...
I am worried that the overheating will have done some damage... headgasket, or liner tho.
 
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