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]

Originally Posted by buddydavis

... 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]

Originally Posted by buddydavis

Will replace the thermostat asap. This should be the 5th one, since the car ran on the road.

You've had five thermostats? 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.
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 , 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! ) Might as well ask an Eskimo about how to build sand castles.
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?