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MG MGF Technical - MGF Water Pump

As a precaution, while doing the 60,000 mile service myself, i decided to change the water pump. i found the UTube video's usefull, before i started.. This one, though not MGF specific ( its a Rover 45 ) at least shows the water pump removal, and what a duff one might look like

I decided not to totally drain the OAT system.. My coolant is sound, totally clean and free of any contamination - and at right on 50/50 concentration.
Upon freeing the pump. of course all the coolant above it runs out, unless one has already drained the system.
Two litres of fluid, was lost on freeing the pump.
I know that, because it took two litres to fill the system up again.. but ive yet to check the bleed circuits.. but i see that the bleeds are about the same level as the pump.. it will be intersting to see what if any air traps were created, by removing just the pump.. i will update.

It is important to totally wash and clean all evidence of old OAT coolant residue off the engine,especially inside the cam belt area, since it will react with any new cam belt one fits and weaken it. I put a running fresh water hose into the header tank and used a brush to make sure that the engine face was totally clean.. then using brake disc cleaner spray, and a dry clean lint free cloth, to be absolutely sure.

The pump i took off, was without fault.. no apparent defects.. no evidence of leaking , sediment, nothing.. it looked perfect.

But.. its a precaution worth doing i think.. seeing the state of the one in the video.. i could easily have found mine in such condition, and even though i did not, the idea of having to take off the cambelt again, because i didnt replace the old water pump, when i was able, is not a consequence i want..
The pump i took off, never had gasket sealant on it.. the ally faces were totally clean and fresh.. but like the video shows, i used minimum sealant to keep the o ring seal in place, though i was very carefull not to introduce anything into the coolant side of the pump.. i think its inviting a subsequent coolant problem to introduce anything, even fragments of gasket sealant into the cooling system.

The pump shows no evidence of leaking.. this evening , and i'm leaving it without fitting the new cam belt, overnight, to be sure tomorrow.

I would be interested to hear any contributions from anyone.. especially if the amount of fluid loss.. two litres, sounds about right..when one changes just the pump.. without draining the system.

N.J. Simon

The seal on shaft of the OE water pump can begin to weep well before 60k miles, so your decision to renew regardless was a Good One ;-)

2 litres does sound about right, that's likely be the volume of coolant that sits above the level of the pump under normal conditions - mostly in the cylinder head waterways but some in the heater matrix too - plus obviously the header tank contents. So although you haven't totally drained the system, the full bleed procedure is required to be confident all air has been removed. Dieter's comprehensive page on this is an excellent reference -

Two other items that preventative maintenance is a Good Thing with are the underbody pipes and the radiator - both have a very finite life expectancy and renewal before they degrade to the point of either leaking or becoming ineffective would have saved many a hefty repair bill. If the rust around the brackets on the underbody pipes has bubbled, not much wall thickness remains so a leak is imminent. Likewise, if the fins on the lower part of the radiator have begun to detach, replacement with ideally an aluminium version (mgtf) should be regarded as 'urgent'.

The pleasure of wide throttle openings is vastly improved when you are supremely confident that the cooling system is in tip top health ;-)

Excellent reply, Bandit, thank you very much.

as an update, today, the level in the header tank had not changed overnight, and no signs of leaks from the new pump.. so, i fitted the new cambelt and alternator belt.. a pig of a job,just because of the limited access - it really wouldnt have been so difficult for mgf to have had a full braced removable inner wheel arch would it.? they went half hearted. and put a crappy flexible lower inner wheel arch.. when what was really needed was easy visibility of the cam belt tensioner.. it took longer for me, to get the tensioner adjustment right than putting on the new belt.. which almost dropped straight on, simply because i had to duck and dive all the time from above ( looking down ) and below ( looking up ) to see the tensioner lined up correctly as i tightened the tensioner bolt. And getting a decent movement on a ratchet spanner to loosen and tighten the altenator is also a pig... simply not enough access..

Anyway.. that done.. i removed the cam lock, and as i did so.. the tensioner moved quite a bit.. so i had to play the same game again..

that done.. i felt brave enough to turn the ignition key.. and all the trepidation passed away.. the engine started on turn.. and purred.

i let it run, for a minute, stopped it, and looked at the tensioner... happy chappy.. so was i.
covers on.. crappy flexible wheel arch on.. i started the engine again and let it warm up.. it took a while.. but no evidence of coolant drop, and no sudden rise in coolant temp.. or oil temp..

after maybe 10 or fiften minutes.. the engine sat running happily, the temp gauge not rising anymore..
a couple of spurts on the accellerator pedal, did not prompt anything abnormal..

Tomorrow, i can lift the car up on the hamer car lift ( another thread ive created here on MGF general ) and spend some time examining the whole of the underside.. including what Bandit has contributed..
So tonight.. its beer time... :) a succesful day..

N.J. Simon

You didn't mention if the radiator fan came on when you let it idle for ten minutes.
If you want some more reassurance that all is well with your cooling system, it might be worth removing the connector from the brown temperature sensor. With the ignition on and connector removed, this should switch the rad fan(s) on - which proves the output cct.
If it doesn't come on, the first stop is F6 under the bonnet which should always be a 20A fuse, not the 15A originally fitted to Fs. It is even more reassuring to leave the car idling until the (reconnected) brown temp sensor has sent a signal to the ECU to switch on the fan. This usually takes 20 minutes at tickover but can be hurried along with the throttle!

Thanks Charless, your right.. ive not yet seen the radiator fan come on.. or heard it, since i bought the car.. 4000 miles ago.. ( it had 52 odd thou on it then, its got 56 odd thou on it now )

But so far, in that mileage ( i do about 90 miles a day on two 45 mile runs, commuting )the water and oil temp gauges always reach the same spot.. and seldom move more than a fraction up or down, once reached..
and though i check the fluid, it has never needed more than a cupfull.. of topping up..

yesterday, my little tickover run.. didnt get the oil warm really..

today.. i need to put back on the rear wheel, and take it for a run.. but, yesterday.. naturally i was reticent to do that.. until i was sure, nothing had changed except the new parts... :)

its going to be a 50 mile return run, to get new tyres fitted.. if i can find somewhere in Kings lynn, open.. :)

when i get back.. i will either be a happy chappy, and ready to look at the things you and bandit have highlighted.. or coming back in a rac van.. :o
N.J. Simon

Ok, getting some 215/40/16 tyres proved to be difficult today.. but i can get some friday, fitted at ATS.. kings lynn.. who sourced 4 BF Goodrich tyres..

215/40 ZR 16 86 W

and i want four ( not 2 that size fitted to rear as per mgf dictate)

And the maker - not fitted by preference, but rather by time and availability.. i cannot so far find any reason not to.

that said.. the run to kings lynn, and the kings lynn traffic, stop starts and idle, ( 50 mile circuit) tells me the engine is happy.. even a 6500 rpm burn in third gear ( i love the mgfs third gear )to pass a slow traffic line, did not provoke any change.. the coolant temp gauge as always, sits steady one position before half way.. the oil temp never got more than about 100, mostly sitting between that and 90..

but rain stops play today.. so.. it will be after i get new tyres, that i start the rest of the 60,000 service

This water pump topic.. is closed now - for me.. the task has been successful.

i might create another topic .. 60 thou service..
N.J. Simon

This thread was discussed between 27/12/2011 and 29/12/2011

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