I'm fixing a recently acquired 1988 F250 w/ 7.5 EFI. Due to various problems caused by incompetent mechanics, the truck had been mostly sitting for the last 2 or 3 years.

Today I finally got everything together and took the truck for a 120 mile test drive. (I needed to use up a tank of partially stale gas before getting a smog check...) About halfway home, the engine started ticking. It appears a lifter has collapsed.

There is an outside chance a rocker arm fulcrum bolt has backed out because yesterday I changed the valve stem seals.

Anyway, despite the clicking, the engine runs and idles fine. I'd like to avoid pulling the EFI and smog stuff back off yet again in order to pull the intake manifold to get to the lifters. Do any of you have suggestions for a "mechanic in a bottle" to try? I have two days left to smog the truck after which I'll need to get daily pumpkin moving permits.

 

You can try loosening the rocker nuts to unload the lifter totally while at idle. They flow a lot of oil thru so they generally don't stick. You can also push down on the rod side of the rocker while at idle to move the internal piston inside the lifter to a different spot.. may break loose.
I'd just ignore the clatter to take the SMOG test, and put a few more miles on to get it real hot before taking the test. More miles means more oil flowing to 'clean' the varnish or whatever is causing the sticky lifter.
tom

 

Try Marvel Mystery Oil down the carb at a fast idle. Not too much at once.

 

The engine is EFI, not carb'ed - besides, how would feeding MMO into the throttle body get to the lifters?

I found out why the lifter collapsed: The test drive used up about 3 quarts of oil. I guess all the puffs of oil smoke when shifting gears added up. Topping up the oil mostly got rid of the click. Adding some of Gunk's Valve Medic banished the click.

I also did yet another compression test (before running the engine.) The test showed that #3 had the collapsed lifter. This is also about where the noise was coming from. (This is the third compression test I've done on this engine. Each time the typical value has gone up.)

As for the oil loss, I suspect I didn't get a stem seal seated properly. The #4 plug had lots of oil soot on it.

My plan now is to swap a good cat in place of the "optimized" cat I've been testing with, and then take it to be smogged.

 

Throw a quart of automatic transmission fluid into the oil and let it run. Used to do it with FE engines all the time. Just did it to a 2.2 pontiac on Friday and the engine ran for one minute with the atf in it and it quieted right down & smoothed out nice

Bountyhunter

 

What?? I've heard of brake fluid in a auto tranny (not reccomended) but never anything like that. Any idea what it does to quiet it down? My moms explorer has a little valvetrain tick from #3, so I might try that.

 

BTW- do you change the oil after you let it run??

 

ATF is a very highdetergent oil and will loosen up a lot of gunge. Throwing a quart into the gas tank helps keep the carbon out of your combustion chamber as well. Yes you should change the oil fairly soon as all the gunge that was in your lifters etc is now in your filter.

Bountyhunter

 

would putting atf in your fuel tank make the engine not fire the mixture right. like water in the gas or something

 

I have a '90 E-350 van with the 460. It's got just over 100K on it, but in recent years I've only been driving it maybe 500 miles per year. I was changing the oil once a year, but I figured it was starting to get gummed up. About four months ago, I fired it up and after a couple of miles it suddenly got a real nasty valve rap on one cylinder. I quickly got it home and shut down. I assumed that it was a collapsed or stuck lifter, and had possibly even taken out a cam lobe.

So, I parked it out back and assumed the worst, that the engine would need to come apart. In a van, with all of that 1990 plumbing and junk, it would have been a serious job. It sat for four months, and I was considering whether to just sell it as is.

Anyway, I read this thread and the tip about using Marvel Mystery Oil to free it up. I was doubtful, but figured there was nothing to lose if the engine had to come apart anyway.

I did as you said and added 1 quart of MMO to the oil, then fired it up and drove off. Within about 5 miles, suddenly the rapping stopped and the engine ran smooth and quiet. I watched the gauges and drove about 30 more miles. The engine seems fine and maybe a little smoother than before. Tomorrow I'm going to change the oil and filter, and I may start adding a small amount (like a pint) of MMO to each oil change to help keep it un-gummed.

So, thanks for the tip! You saved me a lot of money and grief.

 

my 69 lincoln 460 was running rough when I first got it started..it sat for years...marvel mystery didnt help..opened up valve cvrs and found several rocker arms off the valve...put on tightened up till not tick then half turn more... ran air down pushrod into lifter on two cyl helped..good for about 3 min then same...bought new rocker nuts..no good..later found out 69s have to be torqued to 21 ft lbs...no more tick.. all this to say sometimes its the rocker nuts and not dirty lifters

 

If you have C9 Heads you do not torque them down just a 1/2 turn past TDC. Are they adjustable or pedestal mount?


Holy old thread Batman...