7m overheating

[Huz]

After a bit of spirited driving on my way home last night I noticed my engine was overheating. I thought that once I got on the main road it would start to cool down but instead it started to make knocking sound so I put it in neutral and the engine stalled. I lifted the bonnet and there was a fair bit of smoke coming from some ware but I didn’t really take notice as it was late and I just towed it home.
This afternoon I checked the oil and water and it was all good so I started it and it went straight away. So I thought I would just go for a drive around the block and keep an eye on the temperature gauge. The gauge went up to its usual spot and all was good until the top of my radiator split open and steam was pissing out everywhere.
It doesn’t seem to be the infamous BHG as the oil is still black and there’s no steam out the exhaust. So from my understanding the only things that could be causing this is either a blocked thermostat (which I replaced about a year ago) or the water pump has packed it in.
Ok, so before I go out and buy a new water pump and everything I would like to know if anyone has an idea of what else the problem could be.
Your help would be greatly appreciated.

[woggin]

pressure check the cooling system, that'll show BHG or no BHG. is the fan fowling on anything?? maybe that caused the knocking? could be water pump, best bet would be to rip it off!

[big_zop]

Last time that anothers Cressida overheated and it wasnt a BHG, the radiator was blocked. Not sure how that could allow enough pressure to blow the top tank, do you know the history of the car?

Besides that, the thermostat is an easy/cheap item to change and check that the radiator cap is the right pressure rating as well.

[rodi]

Get it carbon monoxide tested, but to build up enough pressure to split the radiator and being a 7M i'll lay bets on BHG

[matty12]

i would almost say your overheating problem came from the tank splitting first and not getting hot and splitting the tank.

Pull the rad out a get a new tank put on it and try again,as long as you havent done any damage you should be sweet,oh and change the thermostat and a teekay test if you can.

[Huz]

I have owned this car for just over 3 years and have never had a problem with the cooling. I just thought it was strange that when it first overheated I didn’t see any steam coming out of the radiator and then yesterday it overheated without the temp gauge going over normal. I have booked it in for a BHG test on sat so fingers crossed.

[TheStitt]

I've BHG'd a few M's 7 and other wise and none have gone to a chocolate milkshake for oil, all have BHG'd just between a water gallery and a cylinder

[allencr]

I've never seen an overheat problem being directly caused by the waterpump though I don't doubt that there have been a few, very few compared to the number of people that always think it's the pump, that were caused by a broken impeller or shaft. Their usual problem is low coolant lever caused by a leaking waterpump or a loose belt. A non-leaking, non-slipping pump causing overheating is a once in a lifetime thing for a mechanic, except for the dealer guys that had to deal with broken plastic impellers years ago IIRC.

[andrew_mx83]

as stitty said 90% of the time they only blow between cylinder and water. only when they get REALLY bad will they mix water & oil. a compression test will tell u for sure and only take a few minutes. start at the back of the engine as thats where they blow

also its not unusual for it to overheat without the gauge going up, if there is no water it will overheat to buggery but there will be nothing flowing past the sensor to give a high reading.


but the ole blocked rad has been coming up a bit recently on mx83's and the tanks are not known for being too good either

[Mr_Flawless]

"yesterday it overheated without the temp gauge going over normal"

This can happen if there is a pocket of air or gas around the gauge sender, it will give an inacurate reading

[dish-oh]

a compression test will tell u for sure and only take a few minutes. start at the back of the engine as thats where they blow

I've heard that compression tests won't necessarily reveal a BHG, (not sure how true it is)

Will some BHG - depending on where it blew, show up in a compression test while others won't?

[Mr_Flawless]

I've heard that compression tests won't necessarily reveal a BHG, (not sure how true it is)

Will some BHG - depending on where it blew, show up in a compression test while others won't?

some will and some wont, if compression comes up normal, than a cooling system pressure test will tell generally.

Smoke is also a good indicator use this as a basic guide, but not a rule.

White smoke = Water = BHG
Blue smoke = Oil = BHG or Turbo Oil Seal
Black = Fuel = Fueling issuses

Compression lock = Cylinder is filled with fluid = BHG (oil or water), Fuel Leak/Issue or U Drove your car into a lake

Mud on the dipstick = water and oil mixed = BHG
Mud in the Radiator = water and oil mixed = BHG

Mud in the Radiator, Mud on the Dipstick and Blowing whiteish bluey smoke = U are the Proud owner of a KIA Carnival

[andrew_mx83]

the only time a BHG wont show on a comp test is if its blown between water & oil only, in which case you will have a milkshake to make up for it

90% of 7m's blow #5 or #6 to water first (causing the overheating from hot combustion gasses entering the coolant)

[matty12]

tee-kay test,this test for combustion gases in your cooling system.It a really quick way of finding if you have a busted head or not,takes about 1min to do the test.

[Huz]

I took my car to a mechanic this morning to have it tested (I think he did a tee-kay test, he had this tube with blue liquid in it). Anyway he said that the car didn’t have a BHG and the radiator was blocked.