Thanks for that Brendan I'll check the coolant.

I also thought I'd add a picture to compare the two types of water pump, the old one that came off and the new type just fitted. The pump is attached using a silicone gasket sealant as it doesn't come with a paper gasket.

Watch the lengths of the screws going back in with the pump. I have seen a few where the casting on the replacement pump was thinner than the original so the screws bottom out and if you aren't fully awake , threads end up getting stripped.

Its been three years and about 25,000miles and the engine has blown out coolant again, total vehicle miles is about 100,00 miles. Engine won't run, coughs and splutters with coolant being forced out of the filler bottle. No previous overheating, temperature needle solid at halfway all the time. No loss of coolant during that period. The only issue there's been is with a very minor hesitation on a light throttle once the engine had warmed up.

Any thoughts on what might be causing it and what I should do next?

Kirok said:

Its been three years and about 25,000miles and the engine has blown out coolant again, total vehicle miles is about 100,00 miles. Engine won't run, coughs and splutters with coolant being forced out of the filler bottle. No previous overheating, temperature needle solid at halfway all the time. No loss of coolant during that period. The only issue there's been is with a very minor hesitation on a light throttle once the engine had warmed up.

Any thoughts on what might be causing it and what I should do next?

Click to expand...

So a sudden rupture of hg....

Sounds like a wapred head or block?

Take plugs out and see which cylinder is leaking worst.... (disable ignition system)

Ziggy

Kirok said:

Its been three years and about 25,000miles and the engine has blown out coolant again, total vehicle miles is about 100,00 miles. Engine won't run, coughs and splutters with coolant being forced out of the filler bottle. No previous overheating, temperature needle solid at halfway all the time. No loss of coolant during that period. The only issue there's been is with a very minor hesitation on a light throttle once the engine had warmed up.

Any thoughts on what might be causing it and what I should do next?

Click to expand...

Repeating the same repair gives you the chance to sell the car as a runner without your current problem.

After removing the cylinder head this is what's found.

https://www.fiatforum.com/attachment.php?attachmentid=198714&stc=1&d=1552706768

https://www.fiatforum.com/attachment.php?attachmentid=198715&stc=1&d=1552706768

The top of the gasket right and left

https://www.fiatforum.com/attachment.php?attachmentid=198718&stc=1&d=1552707124

https://www.fiatforum.com/attachment.php?attachmentid=198717&stc=1&d=1552707124

Bottom of the gasket left and right


https://www.fiatforum.com/attachment.php?attachmentid=198719&stc=1&d=1552707346

https://www.fiatforum.com/attachment.php?attachmentid=198720&stc=1&d=1552707346

There seems to have been some erosion of the gasket between cylinders 3 and 4

There seems to have been some minor cleaning of the cylinder head in piston no 4 shown on the left in this photo.


https://www.fiatforum.com/attachment.php?attachmentid=198721&stc=1&d=1552707644

Kirok said:

Its been three years and about 25,000miles and the engine has blown out coolant again, total vehicle miles is about 100,00 miles.

Any thoughts on what might be causing it and what I should do next?

Click to expand...

Bad luck.. a failure on the middle of winter

Minor suspicion with the antifreeze maybe.?

Did you have 100% faith in the fluid levels being correct..? My only shortterm hg failure was actually a failed heater matrix .. starving the motor of coolant


Swapped the matrix.. done 5yrs without issue.

Charlie

varesecrazy Yes I'm confident that the coolant was fine and that the engine didn't overheat. I was experiencing a very slight hesitation on a light throttle when the engine was warm for a couple of years and was never able to identify the cause. I did replace the ignition module and then the O2 sensor but neither fixed the issue.
I've come to a conclusion that it might have been a crack in the head which opened up when it got warm or else a small leak of gases between the pistons through the head gasket?

I will take more care during the assembly this time and will use a quality Payen head gasket, new head bolts and as a precaution will get a replacement head and have it crack tested and surfaced.

In the Haynes manual it states the torque settings for the head bolts are in three stages. First to 22 ft lbs then 90 degrees and then another 90 degrees. Can anyone please confirm that this is correct?

For information the tap size for the head bolt threads is M9 x 1.25 right hand.

Remanufactured cylinder head fitted

New Payen gasket located on the block

A tip I found very useful when torquing down the head.
The head is torqued in three stages.
First tighten to 22lbft
Second stage tighten through 90 degrees
Third stage tighten through 90 degrees

After the first stage mark the bolts with white paint at the 12 o'clock position and then you can go through the tightening procedure confident that you won't make a mistake.

In this picture you can see that the bolts have been torqued to the final setting with the paint marks on the bolts now at the 6 o'clock position.

I should add that the first time I did this job of head torquing I used a cheap angle device on the socket to achieve 90 degrees. This time I didn't bother with it as a 90 degree arc and the white paint makes it unnecessary and much simpler to concentrate on the procedure without having that cheap contraption getting in the way.

For anyone doing this job it's also a good idea to replace the rubber o ring on the steel water pipe that sits in front of the engine block and fits into the back of the water pump. It's very easy to access with the exhaust manifold and cylinder head removed.