1.8T common component failures

[ibiza_95]

Whats the most common component failure with the 1.8T VAG engine... AGU if it makes a difference?

200sx valve seats seem to be an issue as well as big ends, just wondered what sort of things go on the 1.8T's

Cheers
EDIT: Im hoping torun circa 300bhp thats why its in here

 

[h17och]

at 300 you shouldnt have too many problems.

main things to go are rods and valves tho mate

HoocH

 

[ibiza_95]

hmmm... well the heads just been rebuilt so that 'should' be ok

the rods and pistons will have to hold for now, i cant afford more money on them

I just missed out on a GT28RS on ebay aswell gutted...

Has anyone ever had a problem with big end bearings, mains? im taking the pistons out to have the cylinders re honed so thought if theyre an issue i may aswell replace them... if theyre not i dont see any point in wasting the money on them

 

[h17och]

it not about how new the valves are or when the head was rebuilt.

they are two part valves (sodium filled) as standard and the 2 parts are friction welded together. too much heat can reverse the friction welds.

im sure thats not the only reason for valves dropping tho.

dont forget to use a new oil pump also. good practice n all that

HoocH

 

[Nautilus]

Hello everyone

I revive this thread just because I'm a bit itchy on the problem of valves.

Due to a broken timing belt, had to replace the 8 exhaust valves in my 1.8T (AUQ code).

Our local parts supplier recommended the Intervalve brand for quality, sturdiness and value for money. Alternative were Italian-made valves which were cheaper, but definitely not sodium-filled.

OEM exhaust valves were bent, but absolutely clean, no signs of burning, in the 40,000-odd miles of engine life.

Replaced the exhaust valves (and piston rings, for I had a broken piston ring from unrelated causes), now engine runs fine and has done so for the last 1100 miles.

Description of the Intervalve OEM replacement from a parts supplier website (Eurocarparts) reads like this: "Bi-metal, Hardened valve tip, Chromed valve stem, Stellite covered valve seat".

However, as I roam the Internet, I could not find out if Intervalve brand are sodium-filled like OEM valves, or just plain stainless steel. Dropped also an e-mail to Intervalve to ask if they are sodium-filled.

Assuming they are not, which should be the disadvantages?

Can I expect greater sturdiness from a one-piece stainless-steel valve?
Can I expect valve damage due to heat in a 230-odd bhp modded engine?

Car has never touched throughout its life any fuel below 98RON, and usually runs on 99RON or 101RON, or a combination 50:50 of the two.

Engine has none of the common reasons to run hotter than needed, in practice due to colder sparkplugs, high octane fuels, remap and large diameter downpipe should run a bit cooler than needed.

Thank you,

~Nautilus

 

[h17och]

230bhp....i really wouldnt worry about any of the above mate.

 

[Nautilus]

Got also an answer from Intervalve: they do not use sodium filling in the construction of the valves.

~Nautilus

 

[Nautilus]

Update: here is a report of and experiment performed with Stellite covered valves of similar construction on a classic car:

I put a lot of miles on my MGA, lots of cruising in the fast lane on the expressways, a moderate amount of very serious autocrossing, and more light trailer towing than all other mileage combined. I used to wear out a set of stainless steel exhaust valves every 40,000 miles or so until I started using Stellite exhaust valves. Now I can run an engine 100,000 miles and the valves are still in nice serviceable condition, even though the rest of the engine may have taken a beating by that time. The combination of hardened steel valve seats, Stellite exhaust valves and bronze valve guides is a real winner (giving the bronze guides a skosh extra running clearance for thermal expansion). My last 100,000 mile cylinder head was transferred to another newly rebuilt engine after only minor touch up of the land width on the hardened steel exhaust seats. I have to date never managed to wear out a Stellite exhaust valve, although I do prefer to install new ones when I do a general engine rebuild after 100,000 to 125,000 miles.

http://mgaguru.com/mgtech/engine/ch103.htm

1.8Ts are much sturdier than 1950s roadsters, so we can expect even better performance.

~Nautilus

 

[rsrich]

Supertech valvss, considered by many as "the best" are not sodium filled, but made from a decent high temperature resistant nickel alloy, so no sodium in itself is not an issue. In fact it is possibly contributory to the reliability of the valves due to the nature of the cavity formed in the end of the stem where it joins the head, which inherently involves a join where the sodium fill is, and is the place where they break.
In our race car we dropped an exhaust valve which was brand new genuine Audi and done about 70 miles! Broke off where the head joins the stem...