boost mad

iTrader: (8)

Can anyone tell me what these mean please ?

Also what piston you would say it is . Its out of a saph cossie



cheers

Martin-Hadland

iTrader: (2)

Cosworth part number

boost mad

iTrader: (8)

Standard pistons you rekon ?

AlexF

looks like the valves have hit the piston at some point...

Martin-Hadland

iTrader: (2)

Most YB's look like that

Dirty Harry

iTrader: (12)

standard fitment Mahle pistons mate,looks like you head is well skimmed judging by the dents in the pistons,bets to deck the pistons if your re using the head

Dirty Harry

iTrader: (12)

even when they were brand new but not quite that deep

Martin-Hadland

iTrader: (2)

When new they didn't have those marks

JonnyBravo

Ever considered that a cambelt may of broke at some point ?

Dirty Harry

iTrader: (12)

maybe but I have seen this damage a million times

AlexF

They look more like the marks you get when you mis-time an engine and turn it over by hand.

A snapped cam belt usually looks far worse!

ALex

JonnyBravo

Surely though that is only going to happen if a few things happen

Cambelt breaks
Incorrect cam timing
High lift cams on non pocketed pistons

The head being skimmed a lot "shouldn't" make the clearances that close surely ? using standard cams that is ?

If the valves kissed the pistons like that I would of thought they wouldn't seat correctly after ?

I'm guessing as that mark in the pic is fresh that a cambelt has gone off

JonnyBravo

I have seen a couple go off and the damage has been no worse than that.

I've had to rebuild 2 xe's for people where they haven't tightened the crank pulley bolt to the right torque and its smashed the woodruff key off and untimed itself properly.

One engine was at 8k when it happened and the damage to the pistons was no worse than that, 8 valves inlet side were totalled though

Martin-Hadland

iTrader: (2)

Add over reving on hyd lifters to your list..

dave cos4x4

iTrader: (5)

yep,

i very slightly bent my valves at Bedford a couple of years ago.

the pistons were like then.

there should be other numbers on the opposite side,they will tell you the piston size.

JonnyBravo

Was going to say I'd seen that happen on downshifts, infact I've done it myself going from 4th to 5th and hit 3rd

dumped

Would check the valves are straight while you are at it - replaced 10 before after a "competitive" gear shift. engine still made ok power, still ran fine but at rebuild time it looked like that.

boost mad

iTrader: (8)

Have had teh car about 7 months, but it hasnt been used since october. i havnt had a chance to mesure the head yet but doesnt look as thin as some i have had !

I am assuming the head has come off at some point as BBR Stage 2 is stamped in the front so work must have been caried out !

some pictures of each combustion chamber !

boost mad

iTrader: (8)

just to add, to me the valves dont seem that close to the flat area on the head.... i have seem some that were almost touching

AlexF

Looks like its been running rich, but other that that ok from what you can tell in a pic!

boost mad

iTrader: (8)

rich is one word for it.

once i have measured the head i will post it up and see what you all think

boost mad

iTrader: (8)

head measured 138.7 if i remember correctly

Ryan

is it me of does that head look very very very corroded around the water ways?

even eaten large holes in the water galleries?

Chip

iTrader: (3)

Ive not ever taken a YB apart and NOT seen those marks on the pistons, it must be very common!

Ryan

mine hasnt got those.

mines got AE. 0.5mm BWN i think

whatever the hell that means

thought mine were standard 4x4 pistons

Daveysaff

iTrader: (9)

martin-reyland




Thats what happens when you over-rev on std lifters

boost mad

iTrader: (8)

AE is a company that make pistons and maybe other stuff too .

0.5 would be revore size i would think

Jasesapphy

iTrader: (1)

Ryan thats 0.5mm bigger so 0.5 over bore by the sounds of it my marle have 0.5 stamped on from the rebuild

Ryan

yeah deffo 0.5mm over size, knew that but wasnt sure about the AE part as i've never seen them before, expect them to be YB or Mahle ones

JonnyBravo

Do AE even make forged pistons ?

Corrosion is quite normal Ryan, crap mix of anti freeze or none at all can cause that or a lot worse.

jameswrx

Wonder what my old 4x4 cossie's pistons looked like after a installed the cambelt wrongly

I'd just changed the lifters and rang a co. up to ask about the timing marks (this was 10 years ago) and they told me the wrong mark on the bottom pulley (there was 2 IIRC?)

Fired her up.. ooo noisey, be ok prob just the lifters.. take it for a run, still tapping hard.. hmm. Ring someone else.. they tell me it's the other timing mark

Set it up right and nice and quiet. Ran it for ages after that, seemed ok.

I dunno what it is about cossie engines, but don't they look a mess when you pull them apart. I've messed around with a couple and they are allways looking a state. You pull apart a Jap engine of similar age and they seem so much fresher.