imjdoggie Posted September 29, 2008 Share Posted September 29, 2008 OK guys I have had it waaaaayyyyyyy past my eyeballs on these cars. My problem is we keep having valve issues, we are on our 3rd motor and we have had the same problem with all of them, the Valve's keep sticking. The only thing we can think of is the gas tank still has some OLD fuel in it and the newer fuel (ethanol) is loosening up the junk in the tank and sending it through the system thus making the valves stick. Any other ideas of what may be causing this???????? Thank you in advance, Jason Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted September 29, 2008 Administrators Share Posted September 29, 2008 Hmmmm. Doesn't make sense. Are you positive it is sticking valves? Stuck valves is not a common issue from bad gas. We need more info. Are these fresh rebuilds, junk yard motors, what maintenace, etc. Is this EFI carb etc? Quote Link to comment Share on other sites More sharing options...
PanzerAce Posted September 29, 2008 Share Posted September 29, 2008 Without knowing more about the specific situation, it sounds like you need to clean the heads up before you start running them. If there is old gas in the tank, you probably aren't rebuilding the motors before you use them, correct? If that's the case, it probably is just the age of the motor and parts that is causing this. My advice is just tear a motor down completely, do a rebuild, and then you should be good to go. Quote Link to comment Share on other sites More sharing options...
Challenger Posted September 29, 2008 Share Posted September 29, 2008 If its a dirty tank, why dont you clean it.... Also I dont see how a valve can just stick... wouldnt the engine just not turn over then? What was damaged? Quote Link to comment Share on other sites More sharing options...
Clifton Posted September 30, 2008 Share Posted September 30, 2008 The only valve I've ever had stick had the head bent about 30*. Can a straight valve just stick and over come the spring pressure? Quote Link to comment Share on other sites More sharing options...
Challenger Posted September 30, 2008 Share Posted September 30, 2008 Thats what I was thinking^^^ Youd have to have it major wedged in there for it not to move. I couldnt even imagine it.... Quote Link to comment Share on other sites More sharing options...
imjdoggie Posted September 30, 2008 Author Share Posted September 30, 2008 I purchased a 78 280 2+2 from a guy in NJ, I drove it 2.5 hours home and it ran fine but it had major rust issues. I also have a 280 (SAT FOR YEARS) that has a half decent body with little rust, I removed just the engine and trans from the 2+2, nothing else. I have a set of SU carbs that I purchased from a member online here I removed all the emissions crap from the motor and put the SU's on, the car ran fine for 15-20 minutes we shut it off for 30 minutes to clean up. We went to start it and a nasty rapping sound is now apparent. There is black tar like #$@% all over the valves and one is sticking now. This will be the 3rd motor that this has happened to, different valves sticking but still the same problem with all 3. HELP!!!!!!!!!! lol. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted September 30, 2008 Administrators Share Posted September 30, 2008 I purchased a 78 280 2+2 from a guy in NJ, I drove it 2.5 hours home and it ran fine but it had major rust issues. I also have a 280 (SAT FOR YEARS) that has a half decent body with little rust, I removed just the engine and trans from the 2+2, nothing else. I have a set of SU carbs that I purchased from a member online here I removed all the emissions crap from the motor and put the SU's on, the car ran fine for 15-20 minutes we shut it off for 30 minutes to clean up. We went to start it and a nasty rapping sound is now apparent. There is black tar like #$@% all over the valves and one is sticking now. This will be the 3rd motor that this has happened to, different valves sticking but still the same problem with all 3. HELP!!!!!!!!!! lol. The black gunk is typical on high mileage engines, and that wont cause your valves to just start sticking. Define "valves sticking" for us, i.e. what the valve is actually doing that makes you think it is sticking? Just hearing a knocking sound does not automatically qualify stuck valves. We need a LOT more specifics as what you are calling stuck valves as it could really be any one or two of a hundred other issues that are typical of old engines that have sat for a while. I'll be honest here. 3 motors, and all three are sticking valves? Not likely. you have a better chance of winning the lottery than actually having 3 engines in a row that stick valves, (unless each head is being rebuilt by the same shop/person). Quote Link to comment Share on other sites More sharing options...
imjdoggie Posted September 30, 2008 Author Share Posted September 30, 2008 I'll have a better explanation for you tomorrow, I'll ask my friend-mechanic to explain it to me better. He has worked on Z cars for years and he is baffled to say the least but like I said I'll get a better explanation tomorrow. I did hear the nasty rapping out of the first 2 motors (sat for years) but the 3rd motor (ran fine, drove home 2.5 hrs.) I was not present. Could the SU's be mixing fuel with the oil and doing damage? Thanks in advance for your help guys. Quote Link to comment Share on other sites More sharing options...
calpoly-z Posted September 30, 2008 Share Posted September 30, 2008 I have first hand seen bad gas cause valves to stick. Granted this was in a tiny 2000w generator, but still it can happen. With this engine, sludge built up on the valve stem so much that it actually seized open in the valve guide. I knocked the valve out with a hammer, cleaned it up with emery cloth, put it back in and the motor was good to go. Now I highly doubt that this is the case here, but just wanted y'all to know that it could happen. Quote Link to comment Share on other sites More sharing options...
imjdoggie Posted September 30, 2008 Author Share Posted September 30, 2008 ^^^^^^^^I am 95% sure this is what is happening to us, but I will print this out for him and find out for sure tomorrow. Quote Link to comment Share on other sites More sharing options...
Clifton Posted September 30, 2008 Share Posted September 30, 2008 ^^^^^^^^I am 95% sure this is what is happening to us, but I will print this out for him and find out for sure tomorrow. You sure you're sure? Because you asked if the SU's could be mixing fuel with the oil. Pull the valve cover and check the valve clearance. If one's stuck it would be obvious. Quote Link to comment Share on other sites More sharing options...
imjdoggie Posted September 30, 2008 Author Share Posted September 30, 2008 ^^^^^it's obvious but I'm wondering if the fuel mixing with the oil is causing the sludge? Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted September 30, 2008 Share Posted September 30, 2008 Try chevron with techron! Actualy I just felt like saying that, sorry for the lame post. bye. Quote Link to comment Share on other sites More sharing options...
blue72 Posted September 30, 2008 Share Posted September 30, 2008 I'm wondering why no one has pointed out the Ethanol bit yet. Isn't it known to degrade seals in systems not designed for its use? Hopefully someone knows a bit more and can chime in, but usually seals and fuel hoses need to be replaced and the timing fiddled with as well to make it run properly on such an old car. Could his valve seals be eaten away by using straight E85? That could certainly explain the excessive buildup on the valves themselves. The more I think about it, the more convinced I am that it is not the motors, but the fuel being put in those motors by the end user. (I've formed a nice little self reinforcing loop, I know, it's not a healthy habit). Quote Link to comment Share on other sites More sharing options...
RedNeckZ Posted September 30, 2008 Share Posted September 30, 2008 Don't know all of the facts yet. Need to know last time the engine oil had been changed? Have you tried to adjust the valves yet? Have you put any thing like Sea Foam into the gas tank? It should clean out the tank and fuel lines of any junk in them. It should also help clean up the valves for you (do this outside, it will smoke alot). Stuck or bent valves, you will have to take apart and fix to correct the problem. Keep us informed and Good Luck, Rich. Quote Link to comment Share on other sites More sharing options...
jerryb Posted September 30, 2008 Share Posted September 30, 2008 How would you check if a valve is sticking when its under spring compression in the head?......did you take the head apart? Did you at least remove the valve cover? How would this "gunk" make it through your carbs without plugging up everything in the fuel system and stalling the engine.?? It sounds like you are trying to run old engines without ever opening them up or doing any sort of inspection ...... AND expecting miracles! Sorry to say this but IMO .....I suggest you use another mechanic. Quote Link to comment Share on other sites More sharing options...
COmputoman Posted September 30, 2008 Share Posted September 30, 2008 I have never rebuilt a motor, but the way I look at it is, When you start to run the motor if anything runs fine for a few weeks or months you can assume the engine is in working order and keep driving on it. If you start the engine and you hear loud noises you might want to start a rebuild Quote Link to comment Share on other sites More sharing options...
sweetleaf Posted September 30, 2008 Share Posted September 30, 2008 What is your fuel pressure at the carbs? You said you just threw the carbs on? Sounds like you may still have the high pressure fuel injection pump feeding you carbs way too much pressure. Is your oil full of gas? That would explain the rapping sound. Check the pressure and let us know. Quote Link to comment Share on other sites More sharing options...
blue72 Posted September 30, 2008 Share Posted September 30, 2008 Another good point sweetleaf. Looks like 3.4 to 4.27 p.s.i. is the normal operating range for the carburettor's mechanical fuel pump. Meanwhile, the EFI fuel pump can reach 43 to 64 p.s.i. before a relief valve opens. Quote Link to comment Share on other sites More sharing options...
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