MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - hesitation at low speed

hi i have a 98 mgf which i have just put back on road(been spending all cash on 68 midget resto now finished) i have noticed a bit of mayo on dipstik and 1 spot of oil in water. levels are ok but going to work at 30mph when foot light on throttle notice some hesitation like kangaroo petrol am going to do filter change (oil and fuel)as soon as possible it is vvc with magnicor kv 85 leads so i dont think they are problem has anybody else had this issue thanks richard
rj hardwick

Largely, this will depend on how much is a "bit of mayo" is - but if a very small amount, then the likely answer here, given the duration of lay up and the atmospheric conditions over winter is that this is simply condensation and is not anything more sinister.

If were talking reasonable quantities of the stuff, then it could be pointing to early stages of a gasket failure, which if caught now need not cost a great deal to put right.

Regarding the hesitation, then as you have a VVC, we can't blame a distributor/rotor arm (the most common cause on pre-2001 MPis) as your car doesn't have them. But I am tempted to blame the ignition system. It is possible that the leads are at fault (very common on early VVCs given the routing of the HT cables)but hopefully your magnecore leads remain in good condition.

How old are the spark plugs? What are the gaps?

If these check out okay, then have a look at the coil packs - if there's any cracking of the casing, they'll need replacing.

Let us know how you get on!

How's the Midget looking? :o)
Rob Bell

I'd suspect a weak spark before any fuelling or other issue, much more likely to have formed some damp in the ignition circuit. However, a poor connection (again, damp likely cause) on the sensors may be fooling the ECU into not giving the correct fuelling/mixture. The process of pulling all the connectors and giving the contact surfaces a good sluice with electrical contact spray has often solved similar behaviour. Avoid WD40 for this, proper electrical contact spray (Maplins, Toolstation etc) is much better suited to dealing with surface oxidation etc.
bandit

thanks rob/bandit working the weekend so will look on next day off midget looks great only took me six years to do!!!! totall rebuild all done by myself apart from paint its the 68 model with slatted grill and bonnet moulding have dug out spare coil pack will change plugs and check leads/change plugs asap what plugs do you reccomend i put platinum in about 3 years ago car is low milage 75k had 38k on it when bought six years ago
rj hardwick

I'd personally go with the standard items (Double Platinum Champion RC8 PYP / Unipart GSP 9652). They're meant to be long life, but many support early replacement.

The correct gap is 0.9mm +/- 0.1 mm. Always check new plugs because, although likely to be in the right ball part (IIRC most plugs are supplied, pre-gapped, at 0.8mm) they could have closed up in transit due to knocking around inside the packaging!
Rob Bell

got up after nights resivoir full of mayo oil in water getting quotes of 700 to fix with belts and pump is this about right and do you recommend changing anything else (looks like the midget is comming out early!!!!)
rj hardwick

That's quite a lot - but I am sure it would probably include a skim of the cylinder head (may not be necessary - so I hope the quote is a "worst case scenario?)

Replace cambelt, water pump and tensioner. Basically a complete 60k mile style service.
Rob Bell

Yeeuch, sorry to hear that 8-( Perhaps coolant getting into the cylinders explains the kangaroo impression...

I'm guessing you don't want to have the Midget running on winter roads longer than necessary, hence not considering DIY? The VVC head does look a daunting proposition to unbolt, and yes some of the manifold bolts will apparently only let go after 30 minutes of being gestured & sworn at, but it is definitely possible for mere mortals. This very thorough guide from Tim Guy is worth a read - http://www.timguydesign.f2s.com/pics/MG-HG-Replacement.pdf

The garage method is likely to only fit new head bolts if the current ones have stretched beyond tolerance, but bearing in mind the role they play I'd consider the extra 30 or so for a fresh set a good 'peace of mind' investment. Likewise the cam sprocket bolt, that's one you *really* don't want to let go...
bandit

will change everything is the rad same as 1.8 mgf as i am going to change this as well (original one still on car probably full of mayo and old anyway) found ali one on e bay for 55
rj hardwick

An ali radiator will be from a TF, but they're a straight swap with the F. If it's from a late model there's a good chance of it lasting longer than a brand new F radiator for less money, wise choice methinks ;o)
bandit

is there anything else i need to do while its off re grinde valves etc ?
rj hardwick

Some heads are worse than others for roughness of casting, particularly around the waterways so a bit of fettling may help smooth the flow. If the valves feel good i.e. tight when closed then unlikely to be much gain in re-grinding IMHO. Or you could really go to town and open up & polish all the ports, then match the port faces to the manifolds, just to make sure you're getting the absolute maximum horses ;o)
bandit

I got Dave Andrews to do a "quick and dirty" port on my cylinder head when the job needed doing on my F. Somehow makes the experience that little more worthwhile, if you know what I mean! LOL

Completely agree with what Bandit has said above - may well be worth looking at the oil and water ways, and clear off any casting edges that may limit flow.
Rob Bell

This thread was discussed between 03/02/2010 and 10/02/2010

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.