Bent pushrod on first start!!
<hr style="color: rgb(209, 209, 225);" size="1"> <!-- / icon and title --> <!-- message --> Its a long post but please help.Ok so heres the deal... My fresh 390 tonite upon first fire bent the #1 pushrod within the first 10 minutes of run time. So what happened is I got the motor to TDC with # 1 plug out and set up distributor to #1. Motor fires up but had a loud exhaust leak I thought. Ran motor for a few minutes to check for leak and realized in my stupidity I still has the # 1 plug out. So I refired the motor again with #1 back in and it made a consistent tick with the revs up and down. I was almost certain it was lifter noise not bottom end and kinda wondered if my .090 restricter plugs in head might now have something to do with it. I have white header wrap that was turning brown in color as the motor got hot. I realized that the #1 exhaust header wasn't changing color though so I felt it while running and it wasn't getting hot. I then knew that cylinder was dead. Removed valve cover and exhaust and intake pushrods on # 1 are totally bent! So now is this some sort of problem deeper inside engine and just a coinsidence or is this just the reason for running the motor with my plug out. The only other thing I noticed is there was some moisture under the valve cover and some whiteish tint(not too bad though) in the oil on the stick. I did forget to cover my engine one nite without my tarp over it and only the lift plate over carb hole and it rained with the lift plate having some open hole to allow in water. The oil level has not risen though as an indication of a water jacket leak in intake or head gasket allowing water in oil and level to rise. How bad is minor water to new motor???

 

O one more thing to add to the weirdness I just noticed that #2,3,4 cylinder pushrods on same same side are all my old pushrods and my #1 pushrods are new ones I purchased. My machine shop checked all my pushrods for straightness when I had all my parts in there when they did a pushrod length check for new cam and told me they were straight except for a couple that for some reason where a tiny bit shorter than the others so I only went out and bought two pushrods cuz they said the others were fine to reuse and then the new ones are the ones that fail. And yes they were the same size as the rest I was very carefull when I matched them up!

 

I'm no mechanic; but had a similiar problem; back acouple years with my freshly hi=po built 302, mine was the # 5 pushrods; my problem was loose lifters, replace rods and ran engine about 200 miles and had the same problem again. Came to be too much space / loose lifter, ( mechanic's fault). He had some weird washer/spacers between nut & lifter to take up the space. I had my heads rebuilt then and so far the problem hasn't reappear. I recommend flushing / draining your oil, cheap assurance agianst your possible water problem. The possible water in the intake vicinty the push rod could of been the culprit to bending your push rod.
Sorry I can't answer exactly.

Mitch

 

I just had this happen to me and my problem was sticking valves. I made the mistake of believing the heads didn't need checking and when I first fired up the engine it ran fine. The next day i started it and I had two cylinders not firing. I found bent pushrods on #1 and #5 cylinders on the intake valves. My problem was due to bad gas that created a gum like substance to accumulate on the valves and make them stick. I had to pull the heads and clean all the valves and make sure everything was good.

If you had water in the cylinders, it could cause a hydro lock that basically keeps the valves from opening due to the cylinder being full of water. You mentioned leaving the truck sitting out in the rain. This is one posibility. Also if you didn't get the pushrods into the lifters correctly or if you didn't prepump up the lifters, this will also cause the same problem. I hope these suggestions may give you something to go by.

 

Never thought about the valves...my heads were all rebuilt not too long ago and then new springs installed just recently by my machine shop. I'm phoning them tomorow for some help and info. This sucks I plan to run in a tough truck 4x4 competition this weekend and I still have to break this thing in

 

It's very important that the machinest control the valve stem heights while doing A valve job. I'd bet after all the machine work was done & a aftermarket rv or even stock cam for that matter, the shafts might need shimmed some or different length push rods. but if the valve stem heights are all over the place ( like it sounds) you're in trouble.

 

There are different length (shorter and longer) push rods available for correcting geometry problems.

 

I would make sure the cylinder is evacuated of any & all fluids & try again ...if it got rained on ,,may have hydrolocked against the valves ..

 

As the above post said, I said the same thing earlier. Do check the cylinders for fluids. Pull all the plugs and turn the engine over. Make sure the cylinders have good compression after you do the pushrods too just to be sure everything is working properly.

 

Update: Happy to tell ya that after replacing pushrods and swapping out oil it runs very nice and oil is crystal clean after about 15 minutes of run time. Only issue I have now is it wants to overheat when the temp gets to about 210. I'm running a new camper special 3 core rad (copper) with a flex fan but without a shroud due to the body lift on truck and a stock shroud won't work unless modified. I'm not running any coolant right now due to not wanting to spill on driveway but will coolant make a big difference while running? I think I'm changing over to a electric fan setup tomorow with a temp sensor that will engage at 180 degrees or so. What do you'all think? O and machinist told me that the cause for the bent pushrods was most likely air lock in the lifters of some sort and had nothing to do with not having spark plug out while running...

 

The fan shroud is a big addition for cooling. Without it, the fan can't cool as it should. I am running a 160 deg thermostat and the 4 core SCR radiator and mine runs perfectly cool. Running just water in hot weather will cause the engine to run hotter. So with that said, it would be better to run a 50/50 mix.

 

The shroud is very important. Water however is a better coolant than antifreeze. It just doesn't lubricate, have anti rust ingredients or protect from freezing.

 

I would drop the rad down & put the shroud on. If you don't drop the rad back down after the body lift the fan is sitting too far down to cool right.

 

So I took the flex fan out and went with a 2 speed electric fan from a 92 Taurus. Very nice setup! I had to build brackets across the rad from flange to flange for a mounting surface. Took some figuring but it works real nice with 3/8 flat bar and all holes tapped for easy installation of fan and no messing around with nuts on the backside!! I'm running an adjustable temperature sensor that can be set to start from 160-220 degrees. Motor runs at a nice 200-210 which as far as I know is proper operating temperature. I might try to get the low speed setup on with ignition power because its not being used now and then the high speed kickin in when needed. anyways motors running nice I'm just havin other driveline issues now .....