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valvetrain questions

xDUMPTRUCKx

NAXJA Forum User
Location
highway to hell
im unexperienced and have no knowledge of vavles. so i need help/advice
this is an 86 2.5 I4.

my spring retainer cracked in half after a high rpm situation, the keepers are nowhere to be found, i found out today the rocker arm is bent(in process of getting a new one) and im afraid even more is wrong that i dont know of. Im afraid that the keepers could have been sucked up and are now desroying stuff. also since the retainer cracked letting go of the keepers did the valve fall into the combustion chamber and damage the cylinder? I dont want to have to pull the head. Ive got new keepers and spring retainer installed, and the rocker arm will go one tomorrow, but is there anything else i should check or look into? thanks guys.
 
If you can, exercise the valve a couple of times and see if it binds in the guide. Roll your pushrod on a flat surface (I use a piece of flat glass) and check the ends for flatness/hammered. Look in the spark plug hole at TDC for that cylinder (piston near the top), if need be, use a mirror and a flashlight, you can see if the valve contacted the piston top and damage if any. Do a compression check. At TDC compare the seated hieghth of the valve with another cylinder, if the valve is deformed you can often see a difference in seated hieghth or measure. Should actually measure the spring hieght also, decompressed and installed hieght. A weak or short spring, might cause problems.
If your suspious of valve sealing, you can do a leak down test.
I wouldn´t worry too much about the metal pieces in the pan, the oil pump won´t suck them up and the chances of them getting into something are slim. Hopefully most of the pieces will come out during the next oil change.
How did you install the new spring and retainer? Did you use compressed air to hold the valve up or fill the cylinder full of stirng. If the valve stayed up on it´s own, you already have trouble, the shaft is bent.
 
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okay i did use the air compressor but i dont even think i had to. i tried moving it but its not into moving very much so i think it is bent as you said. pushrods are okay (miraculous). im pretty dumb when it comes to engines, cause ive never had to work on em. i dont really want to have to pull those keepers and retainers again cause my super old passed down valve spring retainer busted and i have to rent from the local parts store. but now that valve spring seems to be compressed all the time to the point of where the rocker arm just slightly touches it when the spring is relaxed. so it sounds like its bent up right? is this someting i can fix?
 
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When you get it all together again, turn the motor over by hand and watch the valve close. If it hangs or jerks on the way up, it probably isn´t gonna last very long. Compare the hiegth of the seated valve (at the top of compression stroke) with another of the same type (intake or exhaust?). You can use a piece of metal or something, make a tick on it and use it to compare, if you have a good metal rule, you can measure the installed hiegth of the spring and compare with another. The installed hiegth, will tell you if the valve head is deformed much. If the installed heigth is OK, the valve probably isn´t deformed much, but still may not seal real well.
At the top of the compression stroke, there really isn´t much pressure on the rocker where it contacts the valve or the push rod, on most motors you can wiggle the rocker a little.
If it´s an intake valve and it hangs, your probably gonna have back flash through the carb. If it´s an exhaust valve it will pop throught he exhaust. A compression test is a good idea, will tell you quick, if a valve isn´t seating all the way or hanging.
I wouldn´t want to take it back apart agin either. But if you do have to, try pushing the valve stem a little from the side with your finger (or wiggling a little from side to side betwen two fingers), there is a very slight clearnace to the side (like .001-.003), that you can feel, that is supposed to be there.
All in all though the 4 I is a pretty strong little motor and kind of forgiving.
If the valve stem is bent and you run it much, it may tear up the guide, which is a pain to repair and almost impossible to replace.
 
well i ran it until it died. the other three plugs fouled up and it shut off. and after cleaning them with carb cleaner ran it again, so if that would destroy the guid im pretty sure that guide is toast. the distributer needs to be reindexed, and im workin on that, following dr. dynos guide off his page, but i havent quite gotten that down so the comprression test isnt an option, looks like im renting that tool again! and that valve is the second one on the head, so im guessing that is the exaust on the #1 cylinder? i can pick up entire head for prretty cheap, $50-$150. but what is the likelyness that i damaged the piston?
 
Look in the spark plug hole with the piston near the top, you can actually see quit a lot, with a flashlight and if need be a mirror.
Take your time, try not to be impatient. The object is to get it together and running without doing any more damage and /or replacing unnnecessary parts. Or better said, without doing any more damage, get it together, then running.
You can do compression test, without a distributor, pull all the plugs, screw it into one cylinder at a time and crank the motor over a few revolutions. Compression should be the same or close on all cylinders.
Did the motor make any strange noises when it was running? Did you replace the valve seal?
Don´t write off the head too quick, I´ve seen some old 4 bangers run OK will some really large clearnaces, other motors wouldn´t tolerate. The valves and push rods have to be fairly straight though.
Go to the library and check out a Chiltons.
Guide may or may not be toast, it´s only gonna happen if the valve is jammed in there pretty tight and its´run for awhile, valve guides are pretty tough.
 
well it ran terrible like the timing was off, but no noticable noises. I did not replace the valve seal. ive toasted the top end of this motor once before 3 years ago when i first got it, but i had it rebuilt and there couldnt be more than 10k on that rebuild. ive got the haynes manny. you think i should replace the valve seal?
 
UPDATE:

distributer succecsfull reindexed. motor turns and starts up. runs rough, if you let your foot off the gas it dies. so im somewhat getting somewhere.... are valves a swap in swap out operation? like can i buy a new set of valves (found some for $20 on ebay) and just throw those in?
 
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