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1995-2002 Range Rover P38A
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Discussion Starter #1
V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

Hello, everybody,

First time poster with my first Rangey troubles.

P38, 2002, UK spec, 4.6, 95,000 miles (you will excuse interchanging of imperial and metric: it is imported from UK so the odometer is in miles, but this is Botswana and we think in km)

It had a minor service on Thursday, followed by a cross-country gallop on Friday (300 miles at a.... brisk... pace) - it's done 10,000 miles in my posession, all long distance runs, 25-35deg C ambient temperature, never given any trouble. Always ease up for at least 5 minutes before stopping (well, all the petrol stations I use are in 60km/hr speed limits!)

  • Saturday morning 0800hrs I took it into town to go shopping, when stopped and parked I saw steam rising from under the bonnet (20km driving, early morning, 20degC ambient)
  • Closer inspection revealed a narrow jet of coolant spraying out of the joint between the throttle body heater plate and the throttle body.
  • Spray subsided when engine stopped and returned when engine running.
  • Did shopping, bought water to top-up - returned header tank to correct level ~750ml/1.5pt
  • Dropped kids at school and went in search of mechanic by 0900hrs, sedate driving: temperature hit red zone after ~10 minutes, with warning light for a few minutes (definitely less than 5)
  • Bypassed the throttle body heater
  • Topped up coolant with engine running, temp gauge showing normal - about 2litres/4pt, then a "burp" of mucky fluid into the header tank
  • Mechanic shakes head and stops engine
With the benefit of hindsight, I recall some quiet "hiccups" when the engine was idling in the morning while waiting for kids to get organised - much gentler than a misfire, could have been exhaust gasses squeezing through the head gasket?

The mechanic suggests that the leak was caused by exhaust gas entering the coolant - seems reasonable cause and effect to me.

So, did we kill it or can it be resurrected? I'm hoping for the best because I just heard our camping trailer is about to be delivered...
 

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JACK'S GRANDAD
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Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

Kind of confused...
Did the throttle body heater cause the hot running, or was it running hot and making noises before that blew?
If you ran it in the red on the temp gauge for @10 minutes, than it needs a good looking over. It could be ok, but I would imagine a head gasket went myself. Any aluminum motor HATES being run too hot, and these are no different.
Either you or your mechanic needs to do a sniffer test on the coolant to see if there are exhaust gases present in the coolant.

Martin
 

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1995-2002 Range Rover P38A
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Discussion Starter #3
Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

Thanks for the reply leftlanetruckin (by far the best side to drive on!)

Let me clarify: temperature was fine for 300 miles on Friday (and the 10,000 miles before that) and for 10 miles into town on Saturday, the steam only appeared when stopping at the first shop, and subsequent investigation found the leak.

I topped up coolant before going in search of a mechanic, it only nudged into the red for a few minutes after driving for 10 minutes in the direction of the nearest workshop - presumably due to continued loss of coolant.

Based on the slight irregularity in the engine note when it was idling before leaving home I am inclined to think a head gasket had started to give way and the throttle body heater plate was the weakest link as the exhaust gas forced it's way into the cooling system. Does that sound like reasonable cause and effect?

I haven't seen anybody here test for exhaust gases - not even for emission control, only commercial vehicles have an annual roadworthy inspection, all other vehicles keep running until the police catch them!

From a bit of further background reading it looks like a compression test through the spark plug holes would serve the same purpose and also identify which bank/cylinder has let go.
 

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Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

It's probably worth flushing the system, and (with the throttle body heater still bypassed) see how it runs. There's no use stripping a motor for a leaky throttle plate. In fact, where you are, i'd be leaving it disconnected anyway.
 

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JACK'S GRANDAD
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9,235 Posts
Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

I bypass them on every rig I touch, total waste of time 99% of the time.
A compression test is hit and miss with a possible head gasket issue.
You need to sniff the coolant for the presence of exhaust gases.
Here is a kit that is sold over here to do just that:
http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7001006_0361073538
I would personally not drive it until I knew the head gaskets were good. If you do, and it overheats again, you run a very real risk of having a cylinder liner come loose on you. That would mean a total rebuild instead of an easy weekend replacing a pair of head gaskets. If the gaskets are OK, you only wasted @$50, and have the piece of mind that everything is hunkey dorey inside the top end.
Just my .02

Martin
 

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1995-2002 Range Rover P38A
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Discussion Starter #6
Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

Thanks for the input, guys.

It would be great to be able to work on it myself but I a) need a workshop and b) need some spare time for tinkering (as well as not being 300 miles away from it with work)!

As it is, I will probably have to submit to the whims of a local workshop or maybe even the main dealer :-?
 

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Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

if the engine bay was sealed [as it should be] you will not notice any steam whilst in forward motion from a small leak, so it may have been happening for a while before you stopped. a couple of months ago i had a small leak in a plastic joint this cause a very fine and small jet of coolant to spray over a middle injector on the right bank, it had began losing coolant very slow but could find no evidence until it got bigger and i happened to stop. Hope you can save it, as said before test the coolant for gas and a compression/leak down [slightly more involved] test will help ping it also, driving with a head gasket failure may also erode the aluminium as the gas make its escape.
 

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1995-2002 Range Rover P38A
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Discussion Starter #8
Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

Again, thanks all.

Can anybody recommend suppliers who can ship international DHL/UPS/FedEx and accept Paypal?

Main stealer has an appalling track record on delivery and won't touch grey imports!
 

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Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

I am sorry I can´t suggest any supplier who both sends by courier and accepts paypal but I can highly recommend Island 4x4 http://www.island-4x4.co.uk

They always send very promptly by mail - and I have never had a problem. You would need to write to them to ask if they will send by courier and paypal - they usually just want you credit card details like anybody else. My last order took all of 3 days to come from England to New Zealand.

They have, or can get, any parts you might need and are quite a bit cheaper than anybody else. You might want to think about installing a stud kit instead of using bolts on the heads when reassembling - there has been plenty written about them here.
Also Viperover just over the border has written this about the valley gasket - maybe get in touch with him for details and other info. http://rangeroverworld.blogspot.co.nz/2011/12/rover-v8-critical-engine-failure-from.html

Good luck
 

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1995-2002 Range Rover P38A
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Discussion Starter #10
Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

Sorry for the delay in responding - pressures of work, and a recalcitrant Toyota Hilux that I will shortly be dealing with in another forum!

I'm now back in the same location as the Rangie: topped up the coolant and drove home 18km in ~25degC ambient temp (with the Hilux following just in case, maybe the threat of "the car in front is a Toyota and it's towing you" helped?)

I started the engine from cold and added coolant until the header/expansion tank was at the mark "cold level". It took about 3 litres! There were occasional bubbles from the hose entering the bottom of the tank against the bulkhead/back of engine compartment, these stopped after a few minutes - presumably air bleeding from the system due to it's low level?

My mechanically inclined friend (exceptionally competent, only available by 'phone, unfortunately) reckons there would be bubbles appearing in the expansion tank if the head gasket was leaky. The only other movement I can see is flow from the small hose returning from the throttle body heater circuit (entering near front of tank above wheelarch): there don't appear to be any bubbles there either.

After the first 1km the temperature gauge popped up to red, and on opening the bonnet found a small jet from the looped hose where we bypassed the throttle heater plate. A little bit of adjustment stopped the leak and proceeded home without incident, temperature remaining normal, although I kept the revs and speed down: 80km/hr.

Would a leak like that prevent the cooling system getting up to working pressure and cause the overheating?

On arriving home (warm engine) the coolant level was about 5cm/2" below the "cool level," gently releasing the expansion tank cap (engine off) and the coolant rose back to just below the "cold level" mark. Seems strange to me - I would have expected the level to rise when hot. Possible symptom of exhaust gas finding its way into the tank and displacing coolant? Or witchcraft?

Starting it again and letting it come back up to temperature, there is a small flow from the radiator header into the expansion tank through the filler neck - presumably to be expected?

The coolant is an orange colour - it seems this is one of the recognised colours. I only have access to the "regular" green glycol type, is a little mixing going to cause rapid death until I have ruled out head-gasket failure?

The exhaust gas test kit is definitely not available here, so will be ordering one for future reference.
 

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1995-2002 Range Rover P38A
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Discussion Starter #11
Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

Update:

Been busy with work and a nice little trip involving 2000km in 2 days to get there and the same to get back. The Rangey performed flawlessly with the throttle heater body bypassed. No water has been used in the 8,000km since the overheating episode, so false alarm.

Interesting to note that the mechanic diagnosing the dodgy head gasket also offered to buy the car... won't be going near him again.

Thanks for all the advice, hopefully the thread will still be useful to others suffering from similar symptoms!
 

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Re: V8, 4.6: Throttle Body Heater Leak -> Overheated -> Dead?

for parts in Southern Africa, try Philip Glynn in Benoni - www.rangies.co.za. +27119631397 or +27825762879 He can source most parts and also has second hand parts. Tell him Philip gave you his number. Also Dover Spares in Joburg +27114936717. If the throttle body gasket has gone it may indicate other problems - like the water pump or the radiator expansion tank cap or even a head gasket about to go. My car started with odd red temp guage readings then loss of coolant then leaks on the crimping on the radiator header tank then water pump gasket and finally a blown top hose at 120kph outside Heidelberg on my way back from Durban. Repaired the head gaskets and skimmed heads and now it doesnt use any water at all.
 
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