Is this something to worry about? cracked valve seat.
Turbo Mini Forums

Sripped the valves out of the Ex works Group A head and found that #1 and #4 inlet valve seats are cracked

Now, there are hardened exhaust valve seats fitted. So, the way i see it, its not a huge major problem, as long as the exhaust valve seats dont come loose, it doesnt leak coolant and has a reasonably good seal.

Basicaly said fuck it and fitted the thing anyway. Its not a high mileger, its only done 2k since july. The other thing is if it does go pop, it wont matter as the 16v will be going in soon.









What do you guys think?

MS

When I first had the larger exhaust valves fitted to a turbo head way back in 94, I had already noticed very minor cracking.

Over time, these got worse and eventually I had to get a new head.

Dont get me wrong....I hadnt noticed any performance change, I just wanted it fixed, as all 4 cylinders had cracks.
Im sure I drove it for 15-20k from when I first noticed the cracks.

Even after the new head(s) gave me other troubles, I reverted back to the cracked head in a desperate attempt to sort the problem... which it did, and the car ran fine again.
The crack you pictured is very small.....the cracks in mine, albeit directly in the head ( no seats ) were huge !!!
But, if you can easily get them fixed, go ahead....if you cant, I wouldnt worry too much about it.. Not until the crack really starts to get big.

Edited by stevieturbo on 17th Dec, 2006.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

my opinions the same as stevies, but........
it will be at the back of youur mind all the time

I can tell you that although they are small, they will cause you a ballache later on. They will grow and eventually you'll have a water ingress problem and if left you'll end up with poor compression. You can repair cracked heads, but unless its an expensive/rare one its not worth it.

I've seen the future and tbh its Pie

But what's the worst that can happen? The water-jacket is a long way back - I'd have theought you'd lose compression before it hits that?

Stevie has given advice based on experience - which is more than i certainly have. I'd definately run with it; especially as it's a short-term thing...

should be ok but just remember that the exhaust insert could drop which could be pretty ugly none that before , ask t3tone he has a near miss on these.

always looking for them bigger bunches of bannanas

Its a pity I still dont have that head or I'd take some pics. Pretty sure I threw it out when I moved house 3 years ago.

But again...that was valves seating in the cast iron head, not pressed in valve seats. There was never any fear of a seat dropping in my head, as there wasnt any.., and also no real way of fixing it either.

I would doubt a seat will drop easily....but at the same time, given a new pair of seats can be pressed in, and the crack should dissappear...

its bound to be worth doing ????

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Well Im gonna run it, see what i can get out of the engine now with it on.

Heres another one of my fuzzy logic theorys as to why its on the outer two cylinders.

On injection cars the outer two cylinders had a tendancy to run a little hotter. Rover change the manifold slightly to try and overcome this, which apears to work. This was on one of the Group A BMH cars that did both the Nurburghring and the Monty Carlo. The ECU was Webber Alpha. Manifold was fully ported. So if the outer two cylinders have been running a little hotter than the middle, that may explain it. The valve sizes are 35.1 and 30.4mm or there abouts. So theres not realy much there in the cast iron with the exhaust valve seat there. Not to mention being used on endurance events.

I thought the same about the possability of the valve seat dropping out. If it happens it happens. Its all in the fun.

Thanks for the advice

I would not use it as the valve seat might loosen or worse fall out. What heppens then is anyones guess. Have the inlet valve seat machined down, and fit an insert there as well. The exhaust needs to go and a new one fitted there as well. SO:
1.Remove exh. valve seat
2. Fit an inlet valve seat
3. Fit a new OS exh valve seat
= NEW head.

YOu'll need to have the head pressure tested after the inlet seat "area" has been ground. Meaning bofore the seat has been fitted.

The reason why you cannot fit an inlet seat instantly is because the exh seat is so hard it makes the seat cutter "jump".

I used to have a MG1300 when I was a little boy (that´s before some of you were still safely tucked inside daddy´s groin). The original head had a cracked head (between in and ex) that I ran for a couple of years. No inserts though. Apart from slight loss of coolant there were no ill effects. I am not sure if the loss of coolant was in fact related to the cracked head. Anyway, as far as there are no apparent loss of power just run it. The only issue is that if the insert has cracked through the complete cross section it may eventually come loose. But you will cetainly notice if it happens...

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Well, we all look at things in different ways.

If it goes bang it goes bang.

Maybe i have too much money, who knows. But the car is for fun and i enjoy building the engines, so to me its fun. If its broke, i fix it. If i cant fix it i'll replace it. No one has died, no one will die, so theres nothing serious about it.

I think you've all gone soft.

That cost me around £5-6k maybe a little more.

Obviously on a smaller n/a engine, potential damages are much less though.

Add some turbos, the cost increases. Add a few more cylinders.....same..

Add a lot of debris in a Mini transmission....

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I know where your coming from and if it were an engine as you say cost £KKKK's then i wouldnt take the risk, my pocket isnt that deep, but when you take risks, you have to accept the concequencies.

Edited by Sprocket on 20th Dec, 2006.

Why not have the thing sorted while it's all off? Two seats including job here in Norway would be around the £100 mark.

Edit:
I'm going to do the same thing on this head:



Here, the seat is ground on the absolute outside of the insert. I guess a standard insert and 31mm valves would be similar. This means that whent he seat is worn, the insert is scrap. I need to install a bigger OD insert here. That does indeed affect the inlet seat again if you look at the picture.

Fucking morons!

Edited by Vegard on 20th Dec, 2006.