Thread: Cracking blocks and Top Hat liners explained - v8

funny, the yanks couldnt make it hold oil,, and the poms couldnt make it hold water.

It's poor engineering that they didn't use tophat liners from the start of production, I suppose they could drop a few stages on the production line by using straight liners.

I had electrolysis in one barrel on a Mack years ago, sent the block to the rebuilders and the bored and fitted oversize liner which was a crush fit aided with a special glue to seal the water jacket, it was still going leak free after 6 years till it was replaced, maybe glue might work on these Rovers although the radiator pressure is huge on Rovers compared to a Mack.

It hardly happens on 3.5s, because there is more meat between the liners and water jacket.
Maybe in the old days not many cars had aircon also in the UK.

I have owned 3 RRCs and haven't had a slipped liner in 2x3.5 and 1x3.9, however I was very careful to have the cooling sytem working well. I understand that 105C is the absolute top temp you should ever go to. Interesting that the thermos fans only kick in at 102C.

I was talking to Graeme Cooper many years ago, and the main reason they stopped 4.2 conversions was returns with slipped liners. So the engine was designed as a 3.5 and it was the subsequent changes that caused the problems.
Regards Philip A

I must admit I thought that a special sealant was used when installing top hat liners that got around the cracking issue - the underside of the top had was sealed and the sealant sealed the crack against the liner - maybe not best practice and clearly scrapping the block would be better but not always possible.

Yes I understood that Turners and others placed a sealant below and above the crack .

Another problem with cracked blocks is that they "relax" and the preload of the liner loosens which in turn causes the liner to move.

Originally Posted by PhilipA

It hardly happens on 3.5s, because there is more meat between the liners and water jacket.
Maybe in the old days not many cars had aircon also in the UK.

I have owned 3 RRCs and haven't had a slipped liner in 2x3.5 and 1x3.9, however I was very careful to have the cooling sytem working well. I understand that 105C is the absolute top temp you should ever go to. Interesting that the thermos fans only kick in at 102C.

I was talking to Graeme Cooper many years ago, and the main reason they stopped 4.2 conversions was returns with slipped liners. So the engine was designed as a 3.5 and it was the subsequent changes that caused the problems.
Regards Philip A

Driving home at a constant 79-81 coolant temp as the 82 degree inline top hose stat does it's thing on the 4.6...

Cheers

I was surprised at how small the cooling passages between the bores were, hardly worth having them there.

Get an in line stat and you will never look back
just had a day in the mountains numinbah valley behind gold coast
up the ranges temp 77 to 82
82 stat
fantastic
with the dodgy OEM it would have been 105
see my post
cheers