New Liners or New Block????

[daveb500]

after losing water and then finding a very clean exhaust port, I've start the process of identifying the problem. The head gaskets were fine (and its No 3 cylinder anyway so unlikely to be the problem). I've just had the heads pressure tested and they have come back fine. So it looks very likely that its going to be a liner issue. There doesn't appear to be any other explanation.

I was going down the route of tophat liners and then came across this :

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&am...

Looks interesting and only slightly more than new liners.....so which is best?

[rev-erend]

Sorry but they are trying to blind you with science ..

All blocks (after 1997) were ultra sonically tested and graded.

You need to ask what grade and therefore average thickness it is .. and it was just a test to help identify a know weakness ..

A top hat is still far superior but it's more expensive to produce.. but is the best solution to the issue.

A red graded block with top hats would theoreticaslly be the best of the best.

[daveb500]

rev-erend said:

Sorry but they are trying to blind you with science ..

All blocks (after 1997) were ultra sonically tested and graded.

You need to ask what grade and therefore average thickness it is .. and it was just a test to help identify a know weakness ..

A top hat is still far superior but it's more expensive to produce.. but is the best solution to the issue.

A red graded block with top hats would theoreticaslly be the best of the best.

That's the answer I was expecting....I just liked the idea of starting with a second clean block and swapping everything from one to the other....but life's never that easy is it.

Am I right in my assumption that if it isn't the gasket or the head, it MUST be the liners?

[spend]

Have the block pressure tested, if that is OK then you are into second opinions having heads & block pressure tested again.

I am surprised you mention the port being clean, but didn't mention the piston or valves...

[daveb500]

spend said:

Have the block pressure tested, if that is OK then you are into second opinions having heads & block pressure tested again.

I am surprised you mention the port being clean, but didn't mention the piston or valves...

No, the piston isn't clean which I thought was slightly odd too. But it has to be the head or the liner. Just wondering if I should get the head tested again somewhere else before I start on the block. It would be a lot cheaper than getting the block tested.

[spend]

I'd be having a second opinion on the heads then, make sure the pressure test is hot as well. Might even be the valve seat lifting - it can be pretty thin round that area on the BV heads.

Wasn't RiP that did your test was it?

[daveb500]

No. It was a company in Gloucester call S&G Engineering. Dom at TVR Power mentioned the hot water thing as well so I'll be checking that when I pick them back up.

[Guillotine]

leaking in the exhaust port, most probably from behind the valve seat.

very thin there on bigger / ported valves and will only be exposed at VERY high temps.

Block/liner/inlet means a clean piston too.

It can be welded and reseated, but probably best to go for new/better heads

Andy
TVRMonster

[daveb500]

Guillotine said:

leaking in the exhaust port, most probably from behind the valve seat.

very thin there on bigger / ported valves and will only be exposed at VERY high temps.

Block/liner/inlet means a clean piston too.

It can be welded and reseated, but probably best to go for new/better heads

Andy
TVRMonster

So how do you go about testing for that then? Or is that not possible?
Is it safe to assume a dirty piston means it is NOT the liner? Here's a picture of the piston top.




and here's the clean port.

Edited by daveb500 on Friday 5th March 18:53

[Guillotine]

did it steam from the rear?

if so when?

probably loads on start up.

Cant tell from 1 piston shot, got one of the next one?

A

[spend]

That piston is showing some effect of 'steam cleaning', but I'd still get a second opinion on your heads first of all. Dom might be a good choice as he may be able to match your heads up, if they are the problem.

[daveb500]

Guillotine said:

did it steam from the rear?

if so when?

probably loads on start up.

Cant tell from 1 piston shot, got one of the next one?

A

By "from the rear" I assume you mean from the exhaust? Obviously the weather as been colder so some "smoke" anyway when started but it has seemed seem a bit excessive. I've noticed quite a bit of black watery "muck" coming out of the exhaust when cold as well. Presumably water sitting in the exhaust and being expelled when it's started.

Here's all 4 on that side. I've marked the one with the clean port. Do you need a close-up of another cylinder?

Edited by daveb500 on Friday 5th March 19:28

[Guillotine]

id get the heads checked again.
the water will sit behind a closed valve, then drop into the cylinder on start.
if more than 60cc can cause knock as it starts, but you wont here that.

seems most likely from pics. there will be some wash from the expelled water and you'll lose water from header tank obviously.
A

[daveb500]

Guillotine said:

id get the heads checked again.
the water will sit behind a closed valve, then drop into the cylinder on start.
if more than 60cc can cause knock as it starts, but you wont here that.

seems most likely from pics. there will be some wash from the expelled water and you'll lose water from header tank obviously.
A

Thanks for the advice. Presumably, if it was a liner, you would expect to see the piston a lot cleaner that it is (given that the port is very clean)?

[Guillotine]

yeah, i'd say so.

nothing guaranteed, but i would be sure.

get them to pressure test the heads on bleed down, ie up to pressure then leave overnight.
hot heads if possible too. try to get some expansion. even a steam clean bay will get the head too hot to touch.

A

[rev-erend]

My Griff 500 was loosing water and turned out the exhaust port leak was the culprit.

Edited by rev-erend on Saturday 6th March 14:05

[Guillotine]

repair will be around £300, but £800 will possibly get a new / better set.

[daveb500]

I think I'll give Dom a call on Monday....

Thanks - helpful as usual

[blitzracing]

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Just to add to this (the engine is still in bits) that the cam preload had never been set up by TVR, so its suspected valves where fractionly open (leading the the odd pattern between the valves(??) , as the heel of the cam showed significant wear.

[livinblokey]

This might help a bit!


http://www.pistonheads.com/gassing/topic.asp?h=0&a...



sounds like the same problem i had last summer,turned out to be exhaust port holed.