I recently changed the CAT on my 1249cc 2001(Y) fiat punto (5dr) after it cracked and sheared off at the lower weld. The rear rubber mount for the exhaust had split when i was on the motorway, so one expediant repair later im on my way, courtesy of some tie wraps. this however had the effect of putting alot of force back down the exhaus to the lower weld on the cat, snap. :-(

So, £170 quid or so later from my local motor factor, and i have a new exhaust to fit.

Those manifold bolts were a bugger to come off when i changed my head gasket last year, i should have replaced them then!

So, new manifold bolts and nuts, and new gasket and exhaust fitted, good to go, except now it sounds like its a VW camper van. It starts fine, but i seem to have lost a bit of power, and its hesitant to set off espicaially if on a gradient.

it sound like this:



now, it could be that it has always been running rough, but the combination of new cat and gasket has gotten rid of other noises to make this one more obvious, i dont know, but the drop in power makes me think not.

i'm looking into the lambda sensors as a cause just now, as per my other thread:

https://www.fiatforum.com/punto/206872-punto-mk2-lambda-sensor-resistance.html

Any thoughts would be appreciated.

I could be wrong, but when you gave it a bit of gas I could have sworn I could hear air rushing somewhere.

Compression test done? if not then you might want to get a garage to do it.

You're sure it's not a diesel in disguise??

you know, that's something i hadn't really noticed before, just been out to the car and the air sucking noise is even more prominent.

I take it this is not good!

I have a compression tester, i got it for checking the head before i did my head gasket last year, and again after replacement.

never thought about checking it again as I've been focused on the CAT.

Will check it tomorrow evening and report back.

Cheers.

I can hear two obvious sounds...both bad lol
The exhaust is leaking at one of the new gaskets and the cambelt and or tensioner is too tight and causing the whirring sound.

Sadly, the exhaust isn't leaking, i snooped all the joints (using light washing-up liquid mix) and there ware no bubbles (no leaks)

The rough noise is internal to the engine.

The whirring noise could well be the timing belt though, when i tensioned it last year, i torqued it up till i could just get half a twist on the belt, its a bit rough and ready but that's what i was recommended to do. I might try and slacken it off a tad on the next re-build, as it looks like im taking it all to bits again soon anyway!

I took the airfilter box off, and the sucking noise is all coming from the throttle body. The throttle body has a bypass duct on it so the engine can get air when the throttle is closed, its the by pass that is making all the noise. I cant remember it making this noise the last time i had the filter box off, so something is a miss.

so, i took all the spark plugs out again to do a quick compression test (unplugged lt leads, throttle body control leads and injector leads to isolate)

plug 1 was very wet and oily, like a light oil/fuel mix. plugs 2 & 3 were bone dry, as was plug 4, although 4 was very rusty for some reason.

so on with the compression test. results are a bit confusing, i repeated them all twice just to make sure i hadnt made a mistake.

Cylinder 1 - 220 psi
Cylinder 2 - 175 psi
Cylinder 3 - 175 psi
Cylinder 4 - 155 psi

now i've no idea what they should be yet, but its looking like 1 is too high, 2&3 are about right and 4 is a tad low, a bit like Goldilocks and the Three Bears!

so, back to the drawing board for now.

Could be the headgasket going letting the oil in, but why the hell would the pressure be so high?

Where's littlepip when you need him??

Well, i have made some progress. I re-cjecked the timing settings, and although there wasnt much in it visually i took the belt off, reset the cam and crank, and re-fitted the belt. turned it by hand to make sure nothing went clunk, and put it all back together again, i compression tested it before starting, and the results make a bit more sense than before:

Cylinder 1 - 200 psi
Cylinder 2 - 200 psi
Cylinder 3 - 200 psi
Cylinder 4 - 170 psi

looking good!

put a little bit of oil into no.4 and it didn't make any difference.

im thinking that actually its probably ok, this was the plug that was very rusty and i dont think the compression tester is getting a very good seat, i cant get down to the nut to tighten it, so im just going off the rubber hose.

so i fit all the rest of it together and turn the engine over, nothing but click click click coming from the relay box! AARRGGHHH

Happily after much much looking, it was a simple fix, there is an earth bonding lead that attached to the front side of the throttle body, once that was on, she started up first time.

i didnt do the timing tensioner up quite as tigh as last time, but the whirring noise is still there.

the good news is the VW Camper van noise is a bit less, sadly it is still there under acceleration, so possible the timing is still out.

far too tired to think about it just now

will look again tomorrow. ZZZZzzzz

have you actually had a look in cylinder 4? a rusty plug suggests that there's water gotten into the bloody thing.

Iron oxide doesn't normally form on it's own..

Car went in for MOT yesterday, it failed, but not on emissions!

Cant really get a good look into the No4 spark plu hole, i've looked as far as I can with a torch, and it seems to be all clean in the inside, again, from what I can see.
It looks like the rust on the no 4 was maybe from the outside.

im happy with the engine just now, just need to fix my brakes!

Its never ending with these cars, is that why i love it so much!

i think that the head gasket is the problem,from how the engine sounds,and it's probally starting from the plug no4,on the left of the engine.
if you have air in the colant bottle,with big pressure,well... you have a big problem.good luck

gearfinger said:

Car went in for MOT yesterday, it failed, but not on emissions!

Cant really get a good look into the No4 spark plu hole, i've looked as far as I can with a torch, and it seems to be all clean in the inside, again, from what I can see.
It looks like the rust on the no 4 was maybe from the outside.

im happy with the engine just now, just need to fix my brakes!

Its never ending with these cars, is that why i love it so much!

Click to expand...

Try taking off the cylinder head and actually having a look. Plus you could see if the gasket was knackered at the same time.

And yup, it's never ending with these little sods, that's why I've got one

Too high compression is usually a sign of something being in the cylinder and taking up volume. Eg if water or oil were present then they would take up some space and create a higher compression. Also the oil could have been creating results similar to a wet compression test. This could possibly be a result of a leaking rocker cover gasket.

A rusty plug is usually a sign of water, plus you have quite a low compression reading on that piston. 30psi down on the others
Whip the plug out, prevent the car from starting, put a clean rag over the plug hole and hold, have someone flick the starter over and see if anything is left on the rag.

I would certainly keep an eye on this.