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MG MGF Technical - Changing spark plugs
I am about to undertake servicing my MGF - big service, with the exception of changing the cambelt, (I'm not that confident - a job for the MGF Centre me thinks !!!).
Two other items I haven't tackled before are the fuel filter replacement - which looks easy enough but fiddly, and changing the spark plugs.
I have never changed spark plugs before, (I usually have diesels), so I was hoping someone could give me some advice.
Is it a case of unscrewing the old plugs, checking the gap on the new plugs and screwing them in. Do they have to be changed in any particular order ???
Do I just hand tighten them. What can go wrong, (I'm unlucky !!!).
Any advice appreciated.
|> fuel filter replacement|
If you haven't already, get yourself a pipe spanner, this is like a six sided ring spanner, but with a notch to slip it over the pipe, using a normal spanner here will destroy the pipe fitting.
> spark plugs
Follow instructions on the back of the pack, usually do then up with thumb and forfinger till they bite, then add n degrees with a spanner.
No order, but it's best to put plugs in the holes before you drop sonthing into the cylinder ;-)
Usually plugs are 'pre-gapped'
The plugs are very deep in the head, so you will need a long socket extension and a correct socket for the plug, these can be very tight fitting, so grease the rubber and sides before inserting the plug (otherwise when you pull the socket stays in place and the extension comes out!)
lower the plug in inside the socket twisting gently - DO NOT DROP, the head is made from alloy and is very soft, take care not to cross thread, drop plug or overtighten.
leave the wires connected to the cap, than it's obvious where they go back cos of the lengths.
|Some directions on changing spark plugs on the F can be found here: http://www.mgf.ultimatemg.com/group2/DIY/maintenance/ignition/replace_sparkplugs.htm|
Derren, I don't know what year/ model of MGF you've got, but if your car has a distributor, I'd recommend that you replace the distributor cap and rotor arm as they're both prone to degeneration and seem prone to oversight on the MG service schedule - more here: http://www.mgf.ultimatemg.com/group2/common_problems/distributor/stuttering.htm
|Make sure you use the recomended plug type, I would also change plug leads at the same time. As a complete amateur I managed this task using Rob's instructions.|
Most DOHC engines have deep recessed spark plugs.
As already stated, use a proper spark plug socket and extension bar.
Look inside the spark plug socket. If the socket has a rubber bit inside it, then it will grip the plugs when loose and allow you to withdraw it up out of the recess. And will allow you to put the plugs back.
If you have a spark plug socket without a rubber bit inside it, then the spark plug will not withdraw up when loose.
What you will need then is to aquire a highly complicated and technical piece of equipment......... a 10" piece of ordinary garden hose.!
Just push it onto the plug (once loosened) and presto, it comes up. Also use for putting back. Just twist plug in until it grips and then pull up the hose. Then use socket to tighten.
Have you made up a list of what you will do to the car for this service?
|Derren, make sure you get the Service Schedule from Dieters (or Pauls?) site.|
|Do you reckon any garage will be able to change the cambelt or should I stick to a specialist. This is the only thing I am cautious of doing myself.|
Obviously I have no intensions of touching the coolant either - air traps = hgf !!!!
Looks straight forward enough to do from the links. What is the best type of spark plug to get. To be honest, I just go to my local MG Rover parts centre and pay over the odds.
Another question though...
When I've changed the fuel filter, is there a pump, (like diesels), which I need to compress to get the fuel flowing again.
|TBQH you may be better doing the coolant yourself because you are more cautious than MGR/A'n'Other garage and will spend more time making sure it is blead thru properly (your time is cheap!)|
Cambelt is hastle cos you have to remove the engine mount to get at it, but it is exactly the same job on the MGF as on a Rover 214 or Metro, so a good (i.e. recommended) local is your friend here.
MGR sell platimum plugs, these are ment to be good for 5 years, but fall off in quality over that time, they are expensive. 'normal' plugs are good for 2 years, but are much cheaper, so it depends on how you rate the hastle and potential damage* of putting in new plugs every two years.
*alloy is soft, doesn't like lots of threading/unthreading.
|There's another set of instructions for comparison in the MGF FAQ at|
|>> When I've changed the fuel filter, is there a pump, (like diesels), which I need to compress to get the fuel flowing again. <<|
No, petrol fuel pumps are not like diesel ones in this respect Derren. Replace the filter, and off you go. :o)
If you have only worked on diesel engines before, I would advise that you take extra care when working with petrol engines in particular the fuel system.
Be careful that you first depressurize the fuel system correctly.
"Position absorbent cloth around fuel filter outlet union. Loosen fuel filter outlet union to relieve fuel pressure"
You don't want fuel spraying all over the place.
Fuel vapours are very explosive if ignited by a spark or flame (unlike diesel fuel).
When you replace the new fuel filter it will be full of air and not fuel.
I would suggest that after you fit it, turn on the ignition key to "IGNITION" for about 4-5 seconds.
That will purge some air from the filter and pressurise the fuel system prior to starting.
Then give turn to "Start".
|Good point Branko - removing the fuel filler cap helps to depressurise the system before working on the fuel line: afterwards, you get pretty minimal fuel leakage. :o)|
|"removing the fuel filler cap helps to depressurise the system before working on the fuel line: afterwards, you get pretty minimal fuel leakage." As we know to our cost;-) lol|
|Okay, next question...|
How many air bleed valves are there on the MGF cooling system and are they easy to find.
How do you bleed the system, (not sure I'm up to changing the coolant yet though !!!).
|Steve - don't we just? LOL|
Derren, there are three bleed points. Dave Livingstone's bleed procedure is detailed here: http://www.mgf.ultimatemg.com/group2/common_problems/hgf_pages/coolant_bleed_procedure.htm
|Looks easy enough. LOL.|
Can I get access to the valve on the right hand side of the engine without having o remove to e engine cover. I haven't had a look yet but I guess so.
The other two look easy enough to get to.
Do I drain the coolant from the radiator - I'm presuming there is a cap at the bottom of the radiator somewhere.
(Think I may get it changed when I get someone professional to change the cambelt - then bleed the sytem a few times afterwards myself).
|You're going to have to remove the engine cover to get at the sparks.|
Not sure on drain down, but take care with a garage changing the coolant because if they don't do it right then they will overheat the car doing it wrong and by the time you get it back it will all look OK till 6 months later when you get HGF.
|>> Can I get access to the valve on the right hand side of the engine without having o remove to e engine cover. I haven't had a look yet but I guess so. <<|
Realistically, this is an inspection cover off job, which is easy enough to do :o)
|BTW, there is no drain plug: the workshop manual states that the hose clips holding the engine coolant hoses to the under body coolant pipes need to be loosened, and the rubber hoses disconnected.|
So basically drain.
Fill expansion tank to full and run the engine with heater on hot.
Leave expansion cap off and let water flow through, and keep filling expansion tank whilst engine running.
Check bleeding valves 5 billion times to make sure no air locks.
|You should initialy fill the system and bleed thru without running the engine, running the engine is a "last of the bubbles" job.|
Also I would remove the small bore hose to the inlet manifold and fill the system till you see coolant comming from here as a first step, that way you know the jiggle valve is free and the engine has coolant thru the whole of the head.
|if you don't get coolant from here (it should drip thru rather than pour) then attach a hose and blow into the head to free the ball, then try again.|
|Is the pipe from the inlet manifold the narrow pipe that goes in to the top of the expansion tank. |
Is it the pipe that is on the right hand side of the engine, (looking at the engine from inside the car).
I'm also having trouble finding one of the bleeding valves - the one inside the engine - not sure if I'm looking in the correct location. Again, is it on the right hand side looking at the engine from inside the car. ????
As I'm a complete novice and never touched a cooling system before, do you think I should tackle this.
Someone suggested jacking the back up so the expansion tank is higher than the radiator - sound right.
|>>Is the pipe from the inlet manifold the narrow pipe that goes in to the top of the expansion tank. |
Is it the pipe that is on the right hand side of the engine, (looking at the engine from inside the car). <<
If you're talking about the pipe from the jiggle valve from the outlet in the inlet manifold, then yes - but the perspective is from the boot looking through the inspection grille.
>> I'm also having trouble finding one of the bleeding valves - the one inside the engine - not sure if I'm looking in the correct location. Again, is it on the right hand side looking at the engine from inside the car. ???? <<
From inside the car, then yes, it is to the right of the engine. It is on a metal coolant rail. Two perspectives of the bleed nipple on this picture: http://www.mgf.4mg.com/bleed_nipples.jpg (frame C & D)
>> As I'm a complete novice and never touched a cooling system before, do you think I should tackle this. <<
It is certainly within reach of the skills of an amateur mechanic Derren - but if you're not comfortable in performing the job, there is no shame in seeking professional help.
>> Someone suggested jacking the back up so the e expansion tank is higher than the radiator - sound right. <<
Won't necessarily help. Keep the car on level ground and perform the bleed procedure as Dave sets out (it's the same in the workshop manual too BTW).
|the rad is already lower than the expansion tank, jacking the back might add unblead pockets where there wern't any before.|
This is an easy job, but replace the clips with good quality ones, not the cheap jubaliee clips from halfords (or the like) which tend to pinch the hose and will cause you leaks.
This thread was discussed between 02/03/2005 and 04/03/2005
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