Bend pushrod on #4 intake

[zeroaxe]

People,

I need your help/advice please.

This is now the second time that my engine has bent the pushrod and tube on #4 intake. That is why I cant get this engine fired up. After replacing it the first time, I could get the engine fired up and running(although very badly) for a short time until it reaches the point where it dies, or doesnt want to start anymore. I am 100% sure that the reason is this bent pushrod.

Now, this motor has been completely rebuilt with fresh 1776 pistons and barrels. "Supervised" by my previous boss, who is supposed to be a pro. I have mentioned to him the first time about the rod, and asked "Why did this happen?". To which he responded that "it happens". One maybe, but twice in a row..., same rod? I have lost my confidence in him, so I turn to my internet buddies where I am sure, between so many people, I am sure to be able to find the answer/reason. I would hate to strip this motor down to the bone again, but if I have to, I will(have to).

In my time of need, I ask the fountain of knowledge for help.

Thanks fellas!

[wrenchnride247]

Have you checked your valve stem length? Put a straight edge across all the valve stems, and see if they are the same. Also, Check for coil bind on that valve. Hope this helps.

[zeroaxe]

Thanks for the reply. I think that all the valves are the same lenght, as they are all new and bought at the same time. The heads are recon ones, valves lapped and 'slides' freely in the guides. So that leaves the coils(you are referring to the valve springs right?) and rocker arms.

So how would I be able to check the coil bind? Turning the engine by hand it seems fine, but as soon as I start it up, it fuzz-up. Also, how would I go about checking rocker arms for problems(and what problems can I expect?).

Thanks for the input. I will pull the head covers on both sides and check the valve stems anyway, hopefully tomorrow.

Thanks!

[wrenchnride247]

To check for "coil bind" turn the motor over by hand with valve covers off, and watch for the problem valve to be at full lift. Then check the amount of clearance you have between "coils" of the spring. I think the smallest amount you can have is .050(use feeler gauges to check this if you have them) if the gap is bigger, your ok there. Another thing to check (if you can see it through the valve spring) is the retainer to valve guide clearance. This distance should be way more than the "coil bind" clearance (not sure on how much though)

Are the rocker arms new? You might have two different ratios if you got some used ones.

Did the lifters slide easily in thier bores, and with no side to side play?

I'm no "expert builder" by any means, but just throwing ideas for you to try and help narrow the search down. Hopfully some others will help out too.

[zeroaxe]

Thanks for the advice, I will be following it (and others) CLOSELY!

The other night(after you posted it) I read it, but it all went over my head. It was late, and I couldnt really think all that hard(well, I seldomly can! ). I havent given it a once over again(yet), but will do. My first priority is to get that engine out the Vanagon and on the workbench/floor in my workshop(still in the making).

I havent sat on my aR$e though. I have searched the net for "coil binding" as well, for some visual aid. I have not really found something that I could say clears the mud though. Any references would be appreciated though(hint-hint).

I have been thinking about this dilema too. And this is what I have come up with. My previous boss machined the case and heads. The heads was done with the "eye measure" tool. So I think he might have machined the #3 too deep. Giving me a wrong deckhight, causing the intake valve to hit the piston. Would this assumption be correct? This is what I found on STF(which I believe confirms my worries):

Actually Max.. deep flycuts will be the biggest source of rocker geometry corrections. If the heads were stock and the case was stock too, going to 1776cc should not do anthing different..given using stock rods. If you machined the decks of the case and flycut the heads the motor just got shorter. In essence, the push rods got too long and the only way to put the rockers back to baseline is gain some altitude with the rocker posts.

The first time when it happened, I took the other/old head off, because I thought that the valve was sticking. When the head was off, I didnt notice any marks on the piston though. Although, it was 'carboned up', if that makes sense. For new pistons, it was black with a 'crust'. I found that disturbing, but didnt make anything of it, as I was guided by a pro when putting all together. So it must've been right.......RIGHT? I know better now. If you want it done right, do it yourself - after some proper research, if you dont know how already. I realise that I dont know that much, but I am learning, thanks to you guys :agree:

So i am not going further with this at the moment, before the engine is back on the stand and stripped to bare case(with c/rods, c/shaft, cam shaft etc installed), or should I strip it down completely and start from SCRATCH?(i.e. is there anything else that he might've missed inside that would cause serious problems later?).

PS. I do think I have got the Cam manufacturer wrong, but still think the "110" is correct. I will try and found the packaging/ask me previous employer.

[wrenchnride247]

I was starting to wonder if you were getting anywhere. I guess the best way too describe "coil bind" is turn the crank pulley(with valve covers off), and watch the problem valve until it is completly bottomed out. Then if you can't see a gap between each coil of the spring... you have coil bind. I'm sorry i'm not very good at internet directions, more of a "hands on" kinda person.

If the case deck, or heads have been machined different from bore to bore, then you couldn't seal the cylinder too the head correctly, leading to major leaks, or cracked head or case .

As for your cam. When looking at the cam out of the case (i can't remember if you can see this with cam in case, while heads and pistons are off) , you should check to see if the cam gear was installed correct. There is a mark on the cam gear. The lobe on the cam farthest from the gear should be facing DOWN. If not, your cam timming is way off (carbon and oil on pistons, poor running, or not running) then this would be your problem (I forgot about this in previous posts )