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MG MGF Technical - Follow up to coolant loss, ticking etc

Just a *conclusion* to the coolant loss problem I experienced.

Took the car in to Sergeant and Collins in Bromley for an investigation.

After a pressure test it was decided to replace the header tank under warranty. Now I get a water temp guage that fluctuates between one mark below and two marks above half way.

It hasn't gone into the red yet.

I got them to change the oil (6 months old) but the ticking tappet noise remains. I guess it was optimistic for this to go completely??

One other thing we got them to check was the apparent (to my gf) rough running when cold.

S&C performed a Test Book / Krypton Tune, cahnged the HT leads (again under warranty)

Now it runs like a real dog, is prone to stall at low revs (esp reversing) and when the clutch is dis engaged sharply

I would apprecaite any comments

Needless to say - its going back in




p hodson

> Now I get a water temp guage that fluctuates between one mark below and two marks above half way.

if rises when stationary(sp?)
Temp sensor, if moves when moving then thermostat.
Will Munns

Actually it does both these things on the move and stationary.

Got stuck in a bit of traffic last night and noticed the guage rise.

Previous experience indicated that this would return to one mark below half way once I was out of the jam - but it just seemed to keep fluctuating - not wildly but noticeable (especially since I am watching it like a hawk now)

Funny (?) thing is it didn't do this before it was *fixed*
p hodson

If it continues after a little while on the move, then it's probebly a thermostat problem, but given that you've just had work done, it might be an airlock in the radiator - Rob Bell has some info on bleeding the system.

ROB?

Does the fan kick in when the temp rises (no= fan fuse/temp sensor) or as soon as the engine is running(sensor disconnected, should also get high rpm when warm) ?
Will Munns

>> Does the fan kick in when the temp rises (no= fan fuse/temp sensor) or as soon as the engine is running(sensor disconnected, should also get high rpm when warm) ? <<

That's pretty much it in a nutshell Will :o) I completely agree with you: temperature increase when stuck in slow or stationary traffic that can be corrected by turning the heater to maximum or when the road speed increases screams non-operation of the radiator fan.

If a sensor problem, it *might* go some way to explaning the poor running too...

Over heating diagnostics @ http://www.mgf.ultimatemg.com/hgf_pages/related_problems_overheating.htm
Rob Bell

I followed the advice from you guys last time actually asked them to check the fan fuse.

The answer is that I trusted them to do it - should they check for air locks after replacing the coolant?

Not sure about the fan - because it ended up running so lumpy just drove it home and parked it. It goes back to S & C on Friday am

Service advisor was non committal on the phone

Incidentally, the idle speed is about 800 (if I read it correctly) which I consider normal according to past experience.



p hodson

Yep, 800/900 is good when hot (should be 1100 when cold)
Will Munns

It is possible to get a normal idle speed with a questionable sensor connection: all depends on the resistance across the temperature sender. Pop off the plug, and the answer will become clear with respect to the fan operation. Replace the plug and then let the car idle for 30+ minutes and see whether the rad fan ever cuts in. If not, then either the sensor is duff or the connector needs cleaning.

With regard to bleeding the cooling system - yes, they should have ensured that the system was adequately bleed (remembering to put the heater setting to maximum).
Rob Bell

Any thoughts on the low revs / cut out scenario?

Coming up to a junction - disengaging the clutch the revs bomb and then recovers back to 800~900 just as quickly

p hodson

Appreciate the comments guys

Trouble is the idle problem didn't exist before I took it in for the coolant loss investigation

Presumably it was tuned correctly on the Test Book / Krypton Tuner?

Even when it was meant to be running badly it wasn't as bad as it is now. Before it was marginal when it was cold but immproved once the engine was hot.

Despair!

p hodson

>Presumably it was tuned correctly on the Test Book / Krypton Tuner?

No tuning, the MEMS does it all itself.

Try the TPS reset:
switch on ignition (but not engine, just all the red lights)
press accelerator to the floor and release five times
switch off ignition
now start car, this might get rid of the stalling problem, which sounds like a fault in the soft landing.
Will Munns

TPS?

Had a look at the archive and it seems that the process you describe resets the idle stepper motor (?)

This was mentioned as having been reset when we collcted the car last time.

Presumably no harm in re-setting again ?

My dilemma is it went to the dealer to be *fixed* - which caused another fault.

Shouldn't the dealer be responsible for fixing it?

I will however take your advice and give it a try

Cheers
p hodson

Regarding the ticking, have a word with Mike Satur, he recommended an oil additive that helped with this problem on an earlier thread - can't remember the name.

Steve
Steve

Took the car back to Sargeant and Collins on Friday.

They hadn't called by 4.30 to say the car was ready so gf called them.

They had discovered water in the oil and suspect the head gasket has gone !

I wonder why they didn't pick the problem up when they changed the oil 7 days before.

This car is 2001 Y with 16700 miles

p hodson

A gasket failure between cylinders, or a leaking fire-ring could certainly explain the poor running Philip :o( A compression test should reveal this problem, although I suspect that the garage will simply remove the head anyway...

Sorry to hear that bad news :o( Let us know how this pans out.
Rob Bell

Just spoken to S&C - car is now ready.

Explaination of faults as follows

Cooling Fan Motor fuse failure due to short in the Fan Motor - leading to overheating and loss of coolant

Overheating and loss of coolant leading to Head Gasket failure

New fan motor, fuse and head gasket replaced under warranty.

Its interesting that

1.the fuse / fan fault wasn't diagnosed during the first investigation.I guess the workshop just replaced the blown fuse and it wasn't driven for long enough for the cooling fan to kick in and blow the new fuse.

2. The loss of coolant wasn't that much. I have read elsewhere that the cooling system on the F has a capacity of 10.5 litres. I would estimate that when ever we lost coolant it took no more than 0.5 litre to get it back to the half way mark in expansion tank


Conclusion is that it doesn't take much to make the HG fail (?)

Does anybody know if their are new / different HG materials that will prevent this happening again and more importantly if the dealers are using better gaskets?


p hodson

New cam belt and tensioner as well as the above fitted under warranty

Total bill would have been £515
p hodson

This thread was discussed between 28/10/2003 and 06/11/2003

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