I have a 2003 Punto Mk2 1.2 8v, just replaced the head gasket following major blow and had the head skimmed 7 times to get it flat! Rebuilt the car and cleared out water etc that had got into inlet manifold. When I start the car it immediately revs up to 7000+ rpm and chucks out loads of exhaust so I have to switch off immediately before blowing the new gasket! Ideally I'd like to run in the engine gently! Tried removing and cleaning throttle body but no difference, tried unplugging TB connectors but no difference, seems no matter what I do it's determined to rev like crazy once started. When I removed inlet manifold during head removal I did notice what looked like old sealing compound around some of the retaining nuts/studs - I replaced the manifold green rubber gaskets but does it need additional sealing? Any ideas welcome!

it can only over rev because it has too much fuel
start there mate

Thanks for such a quick response, I did remove the injector rail and checked each of them squirts, any guidance on what else to check that regulates the amount of fuel? Many thanks!

not really it doesnt make sense does it,you need air/ compression and fuel so there must be too much of something,are you sure wiring plugs on inlet manifold are right
7 skims sounds ominous though

I'm wondering if there's a bad leak in inlet manifold then ECU thinks throttle is open and compensates by squirting more fuel in? No shortage of compression after 7 skims! Did wonder if I messed up replacing the timing belt but can't see how that would cause the engine to rev it's n**s off all by itself!

Andyjw said:

I'm wondering if there's a bad leak in inlet manifold then ECU thinks throttle is open and compensates by squirting more fuel in? No shortage of compression after 7 skims! Did wonder if I messed up replacing the timing belt but can't see how that would cause the engine to rev it's n**s off all by itself!

Click to expand...

if you smoke try blowing smoke towards inlet manifold as you start it to see if it sucks int in or take throttle body of and try smoking it that way with help of a torch
not simple i know
oh for a smoke machine

s and b said:

it can only over rev because it has too much fuel
start there mate

Click to expand...

To much air, morelike.

Either the throttle butterfly is jammed open (cable? bent spindle? etc) or you have one massive air leak on the inlet side.

How come you needed 7 goes to get the head straight? Did they do it with an angle grinder?

Either they didnt skim a deap amount each time....
Or they are using a block of wood and paper....

Ziggy

Hi Guys, thanks for the answers. The head was badly warped hence need to skim 7 times....apparently they took something like 25 thou off, so should have a higher compression ratio engine now when finally get it sorted! The throttle butterfly valve is fully closed and I even tried stuffing a rag in the other inlet that the ICV uses but it still revs like crazy when started! I'm thinking it HAS to be a bad leak around the inlet manifold allowing masses of air in just as if throttle is fully open. I would try the smoke idea but don't want to allow engine to run for that long at full revs with brand new head gasket! Gonna try removing inlet manifold, check for leaks and maybe re-install it with additional sealant everywhere. I've replaced soooooo much on this car it's like a Jonny Cash special, rebuilt one piece at a time!!!!

iwouid check Map sensor if no inlet leak,

Hi Everyone, I've solved the problem! Ordered a replacement inlet manifold off ebay, fitted today and engine now starts normally. Problem is it's making a very loud rattle! Sounds like a noisy diesel! I'm hoping it's a tappet issue rather than the pistons.....anyone got any ideas? It never made any noise before the head gasket blew and I had the head re-skimmed.

Head gasket on upside down? It cuts all oil flow to the valvegear resulting in a lot of noise, followed by permanent engine damage.

Easiest -- or at least, most conclusive -- way to check is to pull the cam cover, look for signs of oil (you can always crank the engine over with the TDC sensor disconnected to check further).

Steel baffle in the cam cover loose?

Someone took the valves out and got the valve/shim order mixed up?

Thanks, pretty sure head gasket right way....did lots of checks. Will open up cam cover tomorrow and take a look.

Well I took the cam cover off today and there looks to be plenty of oil everywhere so don't think it's an oil starvation problem. Have checked the valve gaps as follows:
1=.35
2=.3
3=.3
4=.25
5=.3
6=.35
7=.25
8=.3

So with the exception of valves 2 & 5 they all seem to be under-gapped, would you agree? If this is the case would you expect it to sound like a diesel? Not sure I want to fork out for a bunch of new shims if it's not the underlying problem Does .5mm make all the difference?

Looks like someone re-cut the valves and didn't tell you. Stock clearance on most FIRE engines is 0.35 - 0.45 inlet, 0.45 - 0.55 exhaust, so some of those are way out.

Does it matter?

Generally if the clearance is too big it'll just be noisy -- the springs will close the valves and performance will suffer a little as the valves will open later. In extreme cases a shim may be spat out which will probably cause the valve to drop. Goodbye engine. I've yet to see this, and don't expect to on a FIRE engine which hasn't been messed with.

If the clearances are too tight, there's a fair chance that the valve won't shut. This will have an impact on performance (effectively the cylinder will never seal properly) but will also mean that the edges of the valves will overheat. This will lead to pre-ignition and eventual valve failure.

Note that you don't buy a "set of shims". You buy individual shims to correct the clearances. You may well find that by shuffling shims you can bring clearances back to where they should be on some cylinders. The tolerances allowed by FIAT are already huge in engineering terms.

Cheapest source of shims is Big Mick at eurocarecare. The Haynes describes the process well.

Many thanks for such a detailed reply, I really appreciate it....I'm now on a personal crusade to sort this engine!! A thought occurred to me...if my valve clearances are too tight causing possible pre-ignition AND I had the head skimmed 7 times to get it flat and therefore possibly increasing the compression ratio, would that have the same effect as the timing being too far advanced? If this is the case would slipping the cam belt back a notch retard the timing to compensate? I much prefer the old days where you adjusted the timing with the distributor....happy days!

I'd expect the skimming only to have had an effect if they'd skimmed it past the "stop" marks.

But pre-ignition is different from detonation -- if you're getting pre-ignition it'll be caused by something hot in the combusion chamber acting as a spark plug -- so playing with the timing will have no effect.

Well you were right about the timing, I tried adjusting the belt both ways and it made no difference, engine still rattles like a mad football fan and exhaust still very smokey! I'm suspecting that when the head gasket blew more damage was done 'down below' and wondering whether to bite the bullet and source a replacement engine....anyone got a good one going cheap? I'd scrap the car if I hadn't already just replaced brakes, discs, exhaust, sump, tool kit, tow eye, window winding mechanism, speaker covers, seats cleaned and full service and new MOT....then the head gasket blows! Grrrrrrr!!

Sometimes retreat is the best form of attack!

But -- in the interest of the environment and long term car use, you might get another engine and pull the head (or get a spare head -- just about any MPI head will fit -- Seicento 1108, Punto, etc): you can then look at the bores in the old engine, pistons, etc.

They're absurdly reliable engines, but Puntos tend to have owners who neglect cars with a vengeance.

Yes you're right, the engine just seems to want to carry on, I suspect it had quite a few years of abuse before I got my hands on it. Just hate the thought of binning what is now a decent car (albeit one with rattles & smoke!). Anyway I really appreciate all your help and advice, I feel I'm becoming a bit of a Punto expert and hopefully this thread will help others.