Cracked block - 6 pot

[jerrytr5]

I've been hunting down an odd noise from the TR5 engine and having exhausted the usual suspects pulled the lump and started to strip it down.

It seems that number 3 has a crack in the cylinder wall. I need to strip the rest of it but I'm thinking that the block is probably scrap.

Particularly odd is that number 4 was significantly down on compression but I can't see an issue, yet number 3 was fine.

One of the local group has a 2 litre six pot that might be available - what are the differences between 2 and 2.5 blocks (apart from the crank/conrods)?

Alternatives might be getting it sleeved or if anyone has a spare 2.5 flat top block please let me know.

Jerry

 

Edited March 9, 2020 by jerrytr5

[oldtuckunder]

Blocks are interchangeable, so are rods and pistons, its only the crank. So if you can get a good 2.0 block and machine to correct bore size you ought to be able to swap all your 2.5 moving bits into it.

 

Alan

[RogerH]

Hi Jerry,

in the words of Frank Carson - it's a cracker.

 

I've heard good reports on K-Seal

 

Roger

[DaveN]

Was it using water? You say the compression was ok so it may be worth getting it rebored as the defect may not go through to the water jacket.

Edited June 7, 2016 by daven

[jerrytr5]

That's an interesting thought. I'll have to see what the machine shop think.

Water and Blucol equivalent, garaged, and we haven't had a particularly hard winter the last couple of years so I think frost damage unlikely.

Jerry

[TriumphV8]

I would make it perfect with a new block, line boring for cam bearings

and bore to 77mm for VW pistons. Its worth the effort and a cracked

block will always be a risk. It must be drilled to 77.75 for the liner what

is not cheap and liner pressed in and than rebored. There is a risk left

that the water will find the way down the way to the oil pan.

 

Used blocks are cheap and widely availiable.

[graeme]

I would make it perfect with a new block, line boring for cam bearings

and bore to 77mm for VW pistons. Its worth the effort and a cracked

block will always be a risk.

Andreas,

 

Do you have a part No for the 77mm pistons?

 

Thanks

 

Graeme

[BlueTR3A-5EKT]

My searching found these - Needs a more knowledgeable person to confirm before you all rush out and buy them....

 

ebay with 76.5 mm bore http://www.ebay.co.uk/itm/VW-GOLF-1-4-Piston-1997-on-87-116100-00-Engine-Nural-VOLKSWAGEN-Quality-New-/331757082389?fits=Car+Make%3AVW%7CCars+Type%3A1.4+16V&hash=item4d3e435715:g:rZwAAOSwqYBWnPNV

or

http://www.ebay.de/itm/Kolben-Nural-AUDI-SEAT-AROSA-IBIZA-LEON-SKODA-VW-GOLF-LUPO-BORA-1-4-16V-696190-/390525278427?pt=DE_Autoteile&fits=Make%3AVW%7CModel%3APolo+Stufenheck%7CType%3A1.4&hash=item5aed1ed8db#ht_4438wt_997

 

Suitable gaskets ??? https://www.elmeso-reban.de/automotive.php

 

What about the Mazda piston usage? http://www.steelconrods.co.uk/index.php?cPath=22_36_92 but they would be 78mm bore

 

What about gudgeon pin to piston top heights?

 

TR6 + 60 pistons used to be fabled as the cheap route for Cosworth engines in Lotus Elite.

 

Peter W

[TriumphV8]

Do you have a part No for the 77mm pistons?

 

There are several from the Polo 1.4 engine.

Both the 8 and 16 valve types fit.

I took the BBY engine type, they are 76.5 stock and 77mm oversize.

They start at 40 Euro each including rings.

Be aware that some work at the small end is required.

The have 17mm pins.

 

http://www.ebay.de/itm/Kolben-VW-1-4-ltr-AFH-AFK-AHW-AKQ-ANM-APE-AQQ-AUA-AUB-AXP-BBY-BBZ-/250942425872

[TriumphV8]

Another one with a nice picture & cheap.

NÜRAL is fully okay

 

http://www.ebay.de/itm/1-Kolben-NURAL-76-5mm-1-4l-16V-VW-SEAT-Skoda-AFK-ANM-AQQ-BBY-BBZ-BCA-AXP-APE-/271445884281

 

Meanwhile I found a piston for 30 Euros, unbeatable price for a very good piston.

Its much, much better than the stock ones. 50 years of piston development are

between them.......

 

Rest of the questions above:

The MAZDA piston is more similar to the TR6 piston, its the E5 and E6 piston.

The MX5 piston is a bit high and top can not be cut down.

The E5 can be cut a little bit if needed but has same height as TR6

Pin is 20mm and needs custom bronze bearing.

Piston has no provision for circlips and needs cutting of pin and

adding a circlip cut and circlips. Pin is soft to be cut with tungsten inserts.

I built an engine with 77.75 bore and its nice.

 

VW piston has less compression height and so block must be decked or

small end must be made excentric. I made several engines with the excentric

bronze bushing. It works perfect and gives longer rod working length.

 

Piston has 17mm pin and is too shallow to accept rod. So rod must be made smaller

or piston must be cut out. I always cut the piston.

 

Gasket is Elmeso as posted and also the cheap silver gasket from non recessed

Rimmer fits, especially for the smaller 76.5mm bore.

 

Some time ago we discussed that pistons are dished what was said to be bad.

I think that is better beause altough it needs milling the head it gives a better shape

of the combustion chamber what all in all must be a benefit.

 

 

Left is a eight valve VW piston, right a TR6 piston.

The bushing in the TR6 rod es for the VW piston and excentric.

The bore has moved upwards to meet the new compression height.

Edited June 8, 2016 by TriumphV8

[GT6M]

can always bung a liner init

 

M

[Rob Salisbury]

liners from Rimmers, in stock, around 30 quid each, but you need a machine shop to bore out the block and install the new liner, details in the workshop manual, but the press needed has to have enough throw to install in one continuous movement

Cheers Rob

[Nick Jones]

Ouch! I'd start with another block. That's fairly big crack.

 

2.5 and 2.0 blocks are still pretty common at reasonable cost. You'd probably best avoid the very early Mk2 2.0L as they don't have the cut-outs at the bottom of the bores for the longer throw crank. They can be fettled to miss and you don't have to remove very much material but it is extra hassle.

 

Later blocks will have the recesses around the bores. No problem - just a different gasket. If buying a bare block, make sure it comes with the main bearing caps and that they are a set (should be numbered). Also that the rear main does not have damage on the thrust surfaces.

 

Nick

[oldtuckunder]

You'd probably best avoid the very early Mk2 2.0L as they don't have the cut-outs at the bottom of the bores for the longer throw crank.

 

Now thats an interesting factoid, as my late MK1 2.0 block which I always assumed was identical to the MK2 does have the cut outs, and yes it is the original block.

 

Alan

[roy53]

i F IT'S A MATCHING NUMBER CAR I WOULD TRY SAVING IT.

 

Several types of engines that are massively over bored use liners so shouldn't be a problem.

 

??? was it left for a long time with may be water laying on the piston ring thus eating into the bore . If yes then it could be just a rebore.

 

ROY

[oldtuckunder]

i F IT'S A MATCHING NUMBER CAR I WOULD TRY SAVING IT.

 

 

 

Or just skim the new block and get the old number stamped on it! What you thought all those matching number classics were real?

 

Alan

[len1]

Or just skim the new block and get the old number stamped on it! What you thought all those matching number classics were real?

 

Alan

???? len Edited June 9, 2016 by len1

[TriumphV8]

If you look at the prices of a Porsche or Mercedes Oldie

you might ask yourself if a TR6 will become a valuable Oldtimer

where somebody asks for matching numbers and pays for them.

 

My preference is a powerfull engine, a perfekt suspension to have

fun in the mountains and high performance fuel injection where I

have a fair chance to start and drive my car under all conditions.

 

A cracked block is a risk and I know that from my Rover that has

its problems with cracks and loose liners. A complete engine is

around 250 GBP at Stoneleigh. Not worth any risk IMHO.

[roy53]

Wow you meen people cheat !

 

Roy

[Guest ntc]

Wow you meen people cheat !

 

Roy

Roy

They try but you need to know what you are looking for

[roy53]

Neil tongue still in cheek

[Stanpartmanpartwolf]

"Blocks are interchangeable, so are rods and pistons, its only the crank. So if you can get a good 2.0 block and machine to correct bore size you ought to be able to swap all your 2.5 moving bits into it."

 

At the risk of seeming pedantic, pistons are certainly not interchangeable, since the rods are identical.

I know someone who once somehow managed to fit a 2L crank up with 2.5L pistons, finish the engine build, & then wonder why it had about 50bhp.

 

That block probably needs a liner; rebore the rest, fit County pistons & MS rods for pennies, as long as you're not going to exceed 6200rpm.

Keep it simple unless you're into motorsport or like complication for its own sake.

[Andy Moltu]

Putting a liner into it may not be a great idea. If corrosion is the cause of the crack then you will likely need all 6 lining and it becomes an expensive job when a swap to a replacement block would achieve the same at a lesser cost.

[jerrytr5]

Thanks very much for all the info and advice.

I'll take the block up to Oselli later this week for an opinion and take it from there.

Bit of a shame really as it was lovely and clean inside and there is very little wear.

Jerry

 

Edited March 9, 2020 by jerrytr5

[DaveN]

Jerry

What was the verdict from Oselli?

 

Dave