12R unleaded at 24K miles damaged exhaust valves

[johnbluerio]

After only 7K miles on leaded petrol and 17K on unleaded with additives the exhaust valves needed replacing after this years trip to Ireland. It appears that using different additives instead of sticking to the same make may have exacerbated the problem over the last 15years.

Plus over the 7K original miles it was never ever driven hard or to the limit and would therefore not have had little protective coating on the valves or valve seats.
So the word of warning is stick to the same additive unless you go for hardened seats and valves and just unleaded.

Unfortunately we are now only 99.99% Toyota the new valve collets are from an Isuzu diesel.
Cost of spares, head gasket set ebay £20.00 and a full set of 8 valves £5.00 also from ebay. Bought a couple of years ago because they came up and I can't resist a bargain.
The plastic on the side of the drivers seat is some of the rarest toyota plastic ever, original delivery protective covering to Hiace seats 36yrs old.
Now back together and fully working order, Engine cover, passenger seat and only one panel removed by unbolting to gain full access to the cylinder head.

[celicasteve]

That's nice work John, good job you bought those parts and stored them and what a good price

[Uncle Bob]

John have you got any photos of the burnt valves ?

[johnbluerio]

I had the valves replaced and seats sorted and reground by a local specialist engineering company, didn't think about photos at the time but the head was away for several days which is why a took a few photos of the engine bay. Now nice and smooth at tickover will do say 2k miles and reset and adjust tappets. Pot 3 had zero compression under test the other 3 were just OK but it was sensible to replace all 8 valves whilst the head was off.
I did think about porting and polishing, but thats considered tuning which effects all sorts of things including insurance (though how anyone would know unless you declared it).
The cost against the performance gain was not worth it.
The Hiace has the aerodynamics of the ouside of a windtunnel which is the limiting factor in any performance gain. We use our other Toyota an AURIS SR180 if we're in a hurry.

[harvey]

Has the head got hardened seats now or originals just sorted out John?