Porous block?

[tvrbob]

Hello Mark, What's the question?

[addi]

Help! My May 94 Chimp is pouring water into the sump but it is'nt coming from the head gasket and the engine runs. I've been told that early Chimp engines can get porous blocks. Anybody know which engine they put in the early Chimps and any idea's.

[david beer]

Its a known fact that the 4.6 rangie had the chance of a porous block, mine did ! It was a very slow water loss though, took me ages to realise it was loosing water, maybe something to do with the fact that all the hoses were replaced twice as "recalls".

[GreenV8S]

Apparently most so-called porus block problems are actually shifted liners. But before you get too worried about major internal problems, check whether it is simply a leaking valley gasket or heater coolant pipe. Either of these could dump coolant into the sump.

[mongoose]

Interesting article from 'how to power tune v8 engines' by des hammil-

Water loss problems caused by block cracking-"this is a common problem with 3.9 and 4.2 litre blocks,and a massive number of 4.0 litre blocks,and quite a lot of 4.6 litre blocks.The 3.9 and 4.2 litre engines seem to suffer block cracking behind the liners of the rear two cylinders(cyls 6 and 8)more than any others.In the long term,approximately 25% of 3.9 and 4.2 litre engines suffer from block cracking.The cracking problem was carried over to the '38A' engines,as fitted into HSE Range Rovers,and when it comes to the 4.0 litre engine blocks approximately 80% suffer cracks.Approximately 15% of 4.6 litre engine blocks crack.
It goes on to say that the coolant should be kept to between 75 and 80oC under all circumstances to help avoid this.It also metions that all blocks were ultrasonically checked after '97 and graded by coloured markings for the block wall thickness at the weakest point.
One thing it cannot tell you is which blocks tvr used.ie 3.9,4.0,4.2 or 4.6 for which cc variant?

[v8 racing]

it is true a hell of a lot of blocks do have pourous blocks in fact i have just listed some top hat liners liners on ebay, but if you are getting water in the oil i doubt it is a liner, when a head gasket or liner goes you get massive pressure presure in the water system but very rarely get water in the oil, the water that is sucked in on the induction stoke stroke gets blown out on the exhaust stroke, i would be happy to go with v8's diagnostics on this and say it could be a leaky inlet manifold gasket and water is dripping into the valley

[mongoose]

v8 racing said:

it is true a hell of a lot of blocks do have pourous blocks ..........

Must admit i was amazed how high those figures were when i first read them.I'm wondering why we don't hear more of it on here.Could it be that TVR used the blocks least likely to crack(3.9) for all the engines that werent 4.5litre?I also wonder if its because were benefiting from running the 82oC stats,compared to what we could be running,ie 88oC or even higher?.

[v8 racing]

it is temperature related! the new ranges run at around 100 deg! i start panacking if my engine goes over 80!