Temp Gauge &oil gauge problem?.

[50dwill]

Well can anybody give me a direction to go in with this problem, started using the tf more at the moment before I have a knee replacement but have noticed even in this cold weather the temp gauge is going higher than normal. Instead of sitting just between low and normal, today on a 40mile run it kept bang on the middle and went up in slow moving traffic to not 3/4 before the front fan came on. Also I notice that when it is climbing if I rev the engine it comes straight back to normal.
Last year had the belts and pump changed when the h/g was done, all last summer ran fine in the warm weather and surprised to see this in the cold weather we are having. Not loosing water, oil temp seems a little high about 120 don't know if it a problem or not?

[talkingcars]

Have you checked the oil level?

[Rob Bell]

Just for clarity: the temperature gauge in question - the oil temperature gauge or the water temperature gauge?

[50dwill]

water temp gauge will check the oil level in the morning.

[Rob Bell]

That makes more sense. In slow moving traffic, the radiator fan is called upon to keep air flow through the rad and the coolant cool.

Unfortunately a couple of problems can occur:
1. The fan can seize up if the car hasn't been used for a while
2. The coolant temperature sensor can be faulty - the ECU will "think" that the coolant is cooler than it is, and therefore will not operate the fan!

A seized rad fan will often blow the relevant fuse - so I'd check that first

More here: http://mgf.ultimatemg.com/group2/common ... eating.htm

[RobboMC]

How long since the HG was done? is there some air still percolating out of the cooling system.
Perhaps another good air bleed is in order, or at least check there is coolant coming out of all 3 bleed points.

[50dwill]

Today ran the car and all fans seem to work ok engine and front rad fan work fine both keep cutting in and out as needed, what is puzzling me is today here it is 4 degrees outside and still the temps are both high?. Oil level is good still no water loss no mush in oil cap and h/g was done January 2015 and everything has been fine until last few weeks.
Now when the car went for a mot in January I asked them to change the oil and filter, it is a Unipart oil filter and receipt say 5/30 oil used. I use fully synthetic oil and I wonder if they have used standard oil could that have caused a problem?

[Rob Bell]

Is the radiator warming up as it should? If not, it could be a sticking thermostat.

[50dwill]

will check that next thanks.

[50dwill]

Well today went for a long run in the car and tried a few things, went for about 30mins at 60mph heater control set to medium while going along all fine with both temps fine, came to slow moving traffic and temps started to rise but the fans both kicked in and temps came down. Then I moved the heater control to hot and came back in similar conditions this time both temps stayed low to normal as I think they should be, returned the heater control to low to cool and the temps rose but again all fans came in.
When I felt the air coming from the front rad through the bumper in was not very warm so I checked the main rad pipes under the car and the n/s was hot the o/s hardly warm, so my thoughts are do I have a problem or not? if so do you thinks It is the thermostat or something different. Main thing it does not boil and I can control it with the heater.

[Rob Bell]

Yes, a problem. The heater contains a small radiator that is surprisingly effective at dissipating heat when the fan is running at full speed: I've used this trick many a time when the rad fan hasn't been kicking in to bring the temperatures down to something resembling normal.

The lack of heat in the rad and the pipes suggest a faulty thermostat.

[ErikB]

so I checked the main rad pipes under the car and the n/s was hot the o/s hardly warm,

I think the thermostat is working, but it looks like the radiator isn't flowing coolant as efficient as it should be.
Any idea if the coolant system is building up some pressure as it should be ?

Sensors seem to be OK: fan kicks in, so coolant temp is measured high by the ECU, the other sensor shows an increased temp on the dash.

[Rob Bell]

Rad feed pipe hot, rad return cold. Exactly what you are supposed to find. That the feed pipe is hot suggests that there is decent flow through the rad, and the cool return suggests that the rad is performing as it should. It's efficiency may not be 100% for a host of reasons, but it doesn't really explain why in traffic the engine is starting to overheat (unless the return pipe is really quite warm?). Particularly if the radiator fan(s) are working as they should.

No harm inspecting the radiator though - original MGF items are made of a material that rots for fun - and if you've got an MGF carefully inspect the radiator. If an alloy one fitted, good news. They last much better. Also check to ensure that there are no air locks in the system - a careful soolant system bleed is a good idea at this point. As Erik says, any reduction in flow/ efficiency of the system could influence cooling.

I still wonder whether the thermostat is opening fully though?

A slightly more worrying thought is that this is an early stage of a head gasket failure - although to be honest, MGF/TF gaskets tend not to fail like this... More usually with water/oil mixing, or with gas bypass past the fire rings leading to compression of the cooling system and both will demonstrate coolant loss.

[50dwill]

The h/g was replaced by mg rover mechanic's Dave in January 15 and a replacement head was fitted then, I have checked the invoice and a thermostat was not fitted at the time. So do you think for the cost get someone to change the thermostat just as a 1st check? I can do a bleeding check but on Friday the 11th of this month I am having a knee replacement and the car will be laid up for a time and could do with trying to get it fixed over this period if there is a problem. Anyone in stoke area fancy a little work plenty of tea to be drunk.

[Rob Bell]

Sadly I'm not tht close - but popping out the thermostat and checking its movement in a kettle seems like a good test to me.

[50dwill]

That would be very painful had a knee replacement Friday and standing is about all I can do at the moment but fingers crossed someone will be able to help if not I am out of working order for a while.