Sticking Valves

[skirkland1980]

Hello. My turbo 2.8L is suffering sticking exhaust valves. This has happened twice this year. It has never happened any other time. It happens during start up. It will run fine then if the car sits a few weeks it will throw off a lash pad. The first time I just reinstalled the lash pad and did a valve adjustment and it was fine so I just thought there was too much clearance. Yesterday it happened again but I think it may valve bent the valve this time. I cannot get the valve all the way up. I did some research and it seems to be common with engines that run leaded fuel as I do. Seems to also happen to engines with high exhaust temps and with valve guides that extend into the exhaust port. I read this in an article regarding aircraft engines. The article said there is no way to fix it but I'm hoping someone here may have experienced this and knows a cure. I was thinking that maybe I need some stainless valves and bronze guides but that's a very big expense if I don't need it. Any suggestions? Thanks.

[BluDestiny]

Where are you getting a steady supply of leaded fuel? 

 

Any chance you can go to E85?

[skirkland1980]

I'm using VP C16 race fuel since I really only race the car as of now. I don't really know what parts of my fuel system are compatible with ethanol. I think ethanol requires bigger injectors? Mine are 540cc so i think that makes them good to about 450 whp?

[BluDestiny]

well I have 1000cc's on my subaru right now and I'm at like 85% duty cycle for full throttle. and I'm at 340whp. I'd tell you to size up to at least 850. The stock WRX has 545's and you can't use E85 with them (to make power). 

 

You'd need to check lines to see if they have teflon (PTFE), the walboro should be good for e85 unless it's a really old one, the aeromotive fpr should also be good. 

 

As for the actual problem of the stuck valve though, I'm assuming you're already going to do a tear down and just want insight as what to use, which I woulnd't know.

 

The only thing I can think of for lowering your exhaust temps would maybe be timing related or going to e85 since it burns cooler. 

[skirkland1980]

Thanks. I'm assuming the problem is that the lead is coating the valve stems then oxidizing over time. I might just switch to bronze guides and keep the stock valves since bronze is a little slicker than the iron guides.

[NewZed]

Seems like you're really stretching the assumptions out.  Leaded gas had been used for many years without valve-sticking problems.

 

Has it been the same valve each time?  Then it's a sticking valve problem, not valves.  Seems like you could fix the single valve problem and be fine.

[skirkland1980]

First it was #6 exhaust, then #1 exhaust. I'm not really sure it's the lead causing it. I ran my camaro for years on leaded fuel and it would sit untouched all winter and not have a problem but it had stainless valves and bronze guides. I'm not using a pre 1970s style fuel. I'm using 115 octane. Its about the most leaded fuel available.

[skirkland1980]

So I removed the head last night and removed the stuck valve. The guide is just rusty. The valve isn't bent or galled. It doesn't make sense. The car has only been sitting about a month. It's sat for much longer with no problem. Head was also just rebuilt in February. I tapped the valve out then slid it back in and now it's moving freely. I'm lost as to why the guides are getting corroded unless it does have something to do with the leaded fuel. I have used water/meth injection in the past but not this year but that would seem to effect the intake valves?