Will my KV6 develop into an overheat problem ?

[buddydavis]

Hi veterans,

Pardon me a naive question.

My KV6 2.5 runs fine. Except one thing puzzled me a lot.

Background: '99 Longbridge built. Head Gaskets are healthy, 3-speed fan works well, aircon fine. no airlock, heater blown hot, no coolant leakage. thermostat status unknown.
Ambient temp: ~25C.
Temp monitor: via IPK or OBD port.

No matter the car run in highway, in traffic, uphill/downhill, the temperature rise to 102C and stay +-3C around there.
Fan turns on at 100C and stay on all the times.
Water circulates (at least) on the bleeding hoses of the tank.

Top coolant hose is red-hot.
**Bottom coolant hoses (and radiator) are just cold / lukewarm.

Does anyone encounter the same ?
Was the thermostat likely stuck ?

Many thanks for your help & opinion.

[MrDoodles]

Temp problems on a V6 are 99% always the thermostat and would be the 1st thing I would change!

[kaiser]

If you are in Hong Kong, that is part of the reason. Hot and humid, and not normally much speed in traffic. That means the cooling fan is doing most of the work, and there is little in form of ram air effect.
The temperatures you see are normal for town traffic and as long as your fan works and the system is filled up, you have no problems. The temperatures you see are not abnormally high.

The V6 engine runs pretty hot, and the main thing to do is to keep an eye on your cooling system, as the gauge is not very informative (stays in one spot at all temperature between 75 and 115 degrees).

The plastic thermostat housing is also prone to crack and can develop leaks without giving any warning.

I would therefore recommend frequent coolant checks, when cold.

[SD1too]

... no coolant leakage ... Ambient temp: ~25C ... No matter the car run in highway, in traffic, uphill/downhill, the temperature rise to 102C and stay +-3C around there ... Fan turns on at 100C and stay on all the times ... Top coolant hose is red-hot ... Bottom coolant hoses (and radiator) are just cold / lukewarm.

With those symptoms it's a virtual certainty that your thermostat is not opening correctly.

My reasoning? 25 degrees is not an excessive temperature and, having cut-in at 100 degrees, your fan should reduce the coolant to 96 in about 30 seconds. My V6 certainly does in those conditions. Kaiser's comments seem more related to the 1.8 engine than your 2.5 so, like Mr Doodles, I recommend thermostat replacement.

Simon.

[buddydavis]

Million thanks.
Yes, this is what i am worrying.
That why everytime starting the car, has to turn on the ipk(coolant temp) or using obd to hook up w/ the cellphone to check the temp.

Will replace the thermostat asap. This should be the 5th one, since the car ran on the road.
I am considering to run a bypass (bridge the return hose w/ the coolant inlet)
Hope that stop the fever slightly.

[buddydavis]

By the way, Kaiser, do you still supply metal stat housing for v6 ? That's a really brilliant handcraft indeed.

[SD1too]

Will replace the thermostat asap. This should be the 5th one, since the car ran on the road.
You've had five thermostats? :eek: That doesn't sound quite right. How many miles have you done? Have they been genuine MG Rover/X-Part items?

Just out of interest, what's the highest temperature reached in Hong Kong during the year?

Simon.

[buddydavis]

yes, it is.
the riding quality is great.
done for almost 120k miles since it is on the road.
change almost everything I can except the ecu, kv6 or jf506e gearbox.
all rover originals.
most unreliable is the rubber/plastic pieces, especially those near to the heat.

had once used the oem parts (cambelts) but that unreliable piece gave me an unforgiving experience in the highway. The belt was broken when running at 70mph. Daren't to use those oem anymore.
ambinent temp ranges from 3c (winter) to 36c (hot summer)

yes, the new one will be the 6th. :bowdown:
I can remember what symptons each issues gave but not in order......overheat due to struck close, cracked, struck open, clot w/ rad steel,...like that..
The access is also very tough.
(this times is slightly different. No overheat, but seems struck close though not sure)

Just wonder, what a joke they put the stat in the deep-V :p:, and in the inlet (instead of outlet side) ?

[kaiser]

[/QUOTE=buddydavis;1117556]By the way, Kaiser, do you still supply metal stat housing for v6 ? That's a really brilliant handcraft indeed.[/QUOTE]

Yes. I do.

But I still think your thermostat is not stuck.
(These guys in England live in a freezer, they wouldn't know what heat is, if it hit them in the head with a thermometer! :getmecoat:) Might as well ask an Eskimo about how to build sand castles.:cool:
Your radiator hose is cold (bottom of radiator), your outlet from the engine (top of radiator) is burning hot. According to you.
That makes no sense.

The original thermostat is not anything to brag about, so I shall be happy to supply you one of mine, but I think you should have a careful look at your fan speeds, the condition of the radiator and you perception of temperature in the various spots.

It might be worth it to get an infrared remote thermometer (being close to China, the prices are reasonable) and then get some readings.

I would suggest you measure the difference in temperature between the top and the bottom hose, and if there is indeed a considerable temperature difference, then maybe the flow is restricted, if there is not, the radiator might be blocked.

Write me at willdo(at)icon.co.za.

[MangoMan]

Yes, I was thinking that about the Rad, hoses should be hot at top and cool at bottom, shouldn't they?

Thinking aloud here; circulation can't get mixed-up can it?

[buddydavis]

thanks Kaiser.
also note mangoman's comments which would be same as what I observed.
maybe ours are variants.

observed that in our kv6, the top hose is connected to the elbow hose (thus, coolant flow from engine -> rad ?)

the bottom hoses return to the stat (with a brewing screw halfway) - coolant flow from steel pipe back to engine via the stat ?.

if this is the case, seems top hot, bottom warm appears rational.
yes, weather like hot and wet can kill.
but bottom cold is something suspicious.....not overheat yet. Will take your advise, observe it again for few days and see if need to drill into the deep-V again. :shrug:

[richardvilla]

hi

How can i keep check of the engine temperature i understand its using the tripometre button? sorry ive only had the car 5 weeks so not used to it yet!

[kaiser]

I am just wondering. How long have you observed the temperatures? And have they increased over time?

I have just read some of my old posts when I monitored the stat closely, and I would often reach 100 to 105 in town. However it would go lower on the level open road, certainly less than 100, even on hot days, but as soon as the speed dropped, the temperature would go up again, until kept in check by the onset of the fan.

I thus don't think that the temperatures are out of kilt for town traffic, on hot days, but let's see.

[SD1too]

observed that in our kv6, the top hose is connected to the elbow hose (thus, coolant flow from engine -> rad ?)

the bottom hoses return to the stat (with a brewing screw halfway) ...
Yes, this is correct for the KV6.

Simon.

[Dorset Bob]

hi

How can i keep check of the engine temperature i understand its using the tripometre button? sorry ive only had the car 5 weeks so not used to it yet!

You can get other information too, other than engine temperature.
Here is the link :smilie_re: http://www.the75andztclub.co.uk/forum/showpost.php?p=145&postcount=1 ;)

[Mr_Shed]

So what would you expect normal running temp to be out of interest.

[MangoMan]

Whether 'Normal' or not - mine runs at 91 - 93 Degrees just about all the time once warm.

[richardvilla]

Thank you Dorset :}

[SapperGB]

what about a blocked rad?

[buddydavis]

the temp is monitored via the IPK (press 1+19+1+7 times) :D, or hooking a OBD bluetooth dongle in the port (and check data on cellphone).

appreciated all the inputs.
since it is the 6th times now, i flush everything and make sure the flow along the coolant lines (incl the rad) is fine.
except no way to check the stat during flushing.

indeed, what make me worry, as some buddies pointed out
- the turning fan does not bring the temp down (but seems keep it steady around 102C) and the fan is almost always on. ~10% more fuel consumption. Feel better power. No overheat yet.

(so, not sure if this is designed, or early symptoms of fault. in early days, the temp vary between 92-105, also got this from the IPK)

well, seems need to put it in observation now, and either fix it by a bypass, or a metal stat (Kaiser's great piece).

[Mr_Shed]

Whether 'Normal' or not - mine runs at 91 - 93 Degrees just about all the time once warm.

Mine seeems to range from 94 to 98 degrees, be interesting to see what other peoples are to gauge average.

[buddydavis]

Hi Shed, that's indeed a good idea, to tell what's normal or abnormal.
Here is my record on '99 2.5 kv6, the obd coolant temp. under situations.

1. With a new stat (82C) fitted
- Ambinent: 25-36C (summer :-))
- 50 highway / 50 city (few mild slopes)
- Coolant: 89 - 99C (sometimes shot to 102-105C on climbing/traffic)

2. With a struck-open stat
- slow warmup. rise to 96C. fall rapidly to 67C in highway

3. With a struck-close stat
- rise to 102C. Shoot to 108 - 115C on climbing. Stay there and fall slowly even the fan is rotating crazy

4. With rad-steel (I swear, NEVER pour this kind of stuff in rad again, as it blocks everywhere, esp. narrow header hose, unexpectedly!!)
(Some simply deposit a polymer along the wall & inside the engine - so reduce its thermal dissipation)
- random behaviour between struck-open and struck-close

5. Now (suspect - 2-year old stat, partial but not fully opened)
- steady at 102C. Rise to 106C when climbing. Fan rotates but seems does not lower the temp much.

Hope these records help.

[Plezier]

I checked what TGB runs at this afternoon on a little run out. Seems with the temperature outside at 11 degrees she warmed up nice and quickly then say at 87 degrees until I left her running whiles I went into the veggies shop. came out as the was running at 91 degrees then.

[jn12]

Hi,

I had a problem where my fan would not bring the temp down from 100 or above, see thread below. Presumed the new stat was slightly out of spec and replaced with new. No problems since!

I would also expect the temps to be a bit higher in your country especially going up hill as well.

http://www.the75andztclub.co.uk/forum/showthread.php?t=75154

John

[SD1too]

4. With rad-steel (I swear, NEVER pour this kind of stuff in rad again, as it blocks everywhere ..
Ah ha! You haven't mentioned this before. ;) It most likely explains why you have had so many replacement thermostats in such a short period of time, and why you are continuing to have problems.

Since using this additive, have you completely drained and flushed your cooling system in an attempt to get as much of it out as possible?

Simon.

[COLVERT]

Nobody has yet mentioned that there might be a problem with the water pump.

Impeller fins have been known to corrode away giving less water flow which sometimes shows itself as; rad top---hot / rad bottom---cool. :shrug:

[buddydavis]

Appreciated all inputs.

The rad-steel thing was a long-time-ago stories......and they were all flushed out in a engine rebuilt caused by another incidence - the tooth in an oem cambelt felling off under heat when running on the freeway !!) .

Some additional mod in the weekend.
Add a bypass hose (near the bleeder) to the bottom of header-tank.
This is to resolve bleeding & allow certain coolant flows (even when the stat is closed.)
But the situation still persists.

This time, here comes a temptation.
I may force the kv6 stat opened, and replace the whole bunch with the 1.8T cooling lines. I think the external stat will then no long be the pain in the V. Cross the finger.
(If doing that, will break the pieces up again, and check the rad+pump).

Can I kindly ask ?
For those normal KV6 case, did the bottom rad feel hot ?
(e.g. Mr_Shed, jn12, Plezier (http://www.the75andztclub.co.uk/forum/member.php?u=21552)).

I tends to agree w/ T-cut & Kaiser - the ecu may seems hunt for the best temp by fueling. kv6 operates efficiently in 95-105C.)

[Plezier]

Hmmm I will have to check but the heating works on mine fine so I am "assuming" that flow is OK. The radiator and fan assembly is only three years old having been replaced by a garage for a previous owner.

The problem with checking the temp of the hoses is of course reaching them but I will try when we use the car later.

[Mr_Shed]

I wont be able to confirm hose temp until the weekend, but will update when I can.

Tony