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Fiat 126 Chat => Fiat 126 Mechanical Problem Solving => Topic started by: nick7nick7 on November 22, 2018, 07:03:09 PM

Title: Low compression when cold, ok when hot
Post by: nick7nick7 on November 22, 2018, 07:03:09 PM

I have a 90 Bis.
Its impossible to start from cold, due to low compression on cyl1 circa 12psi. However, when warm (20c+) the compression measures 122 psi. cyl2 is constant at 126psi

Any suggestions what or how to fix it?
I think it could be piston rings. But im not mechanic.

Title: Re: Low compression when cold, ok when hot
Post by: Gadge on November 22, 2018, 07:33:49 PM

Hi nick, BIS engines LOVE eating head gaskets. I've taken heads off and the old gasket just falls apart between my fingers so I would be suspecting that this has happened to yours, although not as drastic as the one I last did. I think the reason it regains its compression is because as the engine warms up all the components expand due to the heat and it effectively re-seals itself so perhaps a pin hole sized hole has appeared. There are fluids you can use like K-Seal which works like radweld and seals the hole after you've emptied it into your water system but to be honest if a jobs worth doing it's worth doing right so I would opt for getting the head gasket done. It's actually rather easy and well within the relms of a diy-er to do

Title: Re: Low compression when cold, ok when hot
Post by: nick7nick7 on November 30, 2018, 09:42:25 PM

Cheers for that gadge. I recently had the head skinned and pressure treated.
Not done a hundred miles since.

Do you have any idea where I can get one of the copper ones? Or is it a case of making my own?

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Title: Re: Low compression when cold, ok when hot
Post by: Xylaquin on December 01, 2018, 12:04:09 AM

A few suppliers do them:

• https://www.fiat126ricambi.com/fiat126/Gaskets/PK1159
• https://webshop.fiat500126.com/en/engine-parts-und-gaskets/cylinder-head/cylinder-head-gasket-copper-18-mm
• http://www.ricambio.co.uk/69-fiat/72-classic-fiat-126-parts/150-gaskets-seals-grommets-and-rubber-parts/829-copper-head-gasket--fiat-126

Title: Re: Low compression when cold, ok when hot
Post by: nick7nick7 on December 01, 2018, 07:29:53 AM

Cheers matey, not heard of that first shop.

Will it still eat away at the copper ones like it does with the cork version I got last time?

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Title: Re: Low compression when cold, ok when hot
Post by: Xylaquin on December 01, 2018, 10:05:01 AM

Hopefully not, though if your head gasket was made of cork I have a theory what your problem has been  :o

Title: Re: Low compression when cold, ok when hot
Post by: nick7nick7 on December 01, 2018, 10:08:01 AM

Hopefully I'll get it striped tomorrow and see.
Dependant on the weather.

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Title: Re: Low compression when cold, ok when hot
Post by: dajwid on December 01, 2018, 08:39:43 PM

Are you thinking of rocker gasket or head gasket ??

Quote from: nick7nick7 on December 01, 2018, 07:29:53 AM

Cheers matey, not heard of that first shop.

Will it still eat away at the copper ones like it does with the cork version I got last time?

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Title: Re: Low compression when cold, ok when hot
Post by: nick7nick7 on December 01, 2018, 08:55:17 PM

Head gasket


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