3.9 V8 and porous blocks

Not exactly porous - the block can crack behind the cylinder sleeves leaving you with a "mysterious" loss of coolant.

Not really...

A new block is the only way I know of to fix it... any other method tends to work out more expensive !

I have 3 3.9 V8's in different vehicles, none of them have exhibited this problem and there is a tendency to "assume the worst" due to the engine's reputation. The second one I bought had all sorts of weird problems that turned out to be a failed inlet manifold gasket but the scare stories had me convinced It was a faulty block. Fortunately I replaced manifold and head gaskets first and it has been fine ever since.

It is a bit of a gamble but IMV the odds are in your favour and it is a superb engine - keep the EFi on it to get the best out of it.

cheers

Dave W.

Yes. Throw it in the sea. If it's porous, it will float, like pummice. If not, it will sink without trace.

HTH David

So if it floats it's a witch and you get to burn it?

Graeme

I know of one that had this problem (old Rangie) and it was replaced under warranty fortunately. I haven't heard of it as a very common problem (touches wood and prays).

Yup, you got the idea. It could mean it's a duck.

Yes you can find out. Take a look at:

These testers aren't cheap (especially if you don't already have a compressor) but you may be able to find a suitable engine reconditioners, or the like, locally to you that could test it.

For the record I have had two 4.2l (same as 3.9 but with longer stroke) in my LSE in under two years, First cracked at 100thou and a second second-hand engine lasted six months. Now have a RPI tuned 4.6 UMMMMMMM

John

Austin

Checked on that SD1 it is a V8 but unfortunately it has a rod out the side of the block It was high mileage anyway

Mike

They also won't tell you anything about the state of the block. Checking that the piston rings, valve seals, head gasket and liners are OK won't show a leaking block, even a coolant pressure test won't help unless the engine is warmed through and even then may not show anything.

The leaks appear behind the sleeves so in many cases won't effect the running of the engine or it's performance at all. In many cases the leak is so small that it doesn't even cause overheating unless you let the water level drop too far.

cheers

Dave W.

Who diagnosed the problem ?

I ask as I have seen a number of cases where inlet manifold or head gaskets have leaked leading to the engine being diagnosed as having cracked blocks "because the 3.9's all do that". Changing the manifold and cylinder head gaskets has then fixed the problem. On the plus side of that one of our club members got a complete 3.9 and auto for 300 quid because the owner was convinced that the block was cracked - a top end rebuild fixed the problem.

The first 3.9 I fitted (bought second hand, having done about 80,000 miles) had all the classic symptoms and I was told by several "V8 experts" that it would need a new block. A bit of a bugger as I'd bought the engine privately and blown half my build budget on it. Had I had a bit more money I'd have binned the engine on their advice but working to a budget decided to ignore the cynics and try a top end rebuild that I'd planned to do anyway.

3 years later and it's still going strong in my competition motor and doesn't use a drop of water (other than when the fan controller stopped working and it boiled !).

I have seen a genuine case of a cracked block on a 3.9 BUT I have begun to suspect that many of them are incorrectly diagnosed due to it's reputation. The best way to prove the block is cracked is to remove the liner so most are done either on a "all the symptoms fit and it's a 3.9/

4.0/4.2" basis or "we couldn't find/fix the problem therefore the block is cracked" basis.

My own experience probably makes me over sceptical but then I've also seen the bills that people have had to pay to the people that diagnosed the problem.

Don't suppose you still have the 4.2's do you ??? I'm more than willing to test my theory were you to donate the engines :-)

cheers

Dave W.

On or around Mon, 1 Dec 2003 21:51:46 -0000, " Mike Jones Super Hero \(sluff\)" enlightened us thusly:

I'll cross that'n off the list then :-)

there are a couple of 3.5s on ebay ATM, and one known good'un locally, but for more money than i was ideally hoping to spend, also the aforementioned

3.9 which is one of those "a mate of a mate was offered it recently" and thus may not be actually available.