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Discussion Starter #1
I rebuilt my 2.5 back in 01. The truck never made it to the road until 2016, I was out of state that long. I have put 3000 miles or so on this engine as of now. Has ran decent for that time and uses no oil. Curious thing happened. I had to change the starter last weekend and so while I had it that far, I wanted to check the intake for a vacuum leak. Knowing how the intake bolts are aligned top and bottom of the intake, there was a chance I didn't get them torqued correctly 17 years ago. So I took the intake off and cleaned up the manifold and metal gasket and reinstalled the intake. This did cure the vacuum leak, ran good performance wise. As soon as I started the truck up it had a rocker/lifter click. Today upon opening the valve cover and removing the rockers and pushrods, all looked fine. Until I got to the very back pushrod. It was stuck. I mean vise grip removal stuck. It would spin in a circle, but not wiggle at all. All the other pushrods are just dangling around in their journals, this one will not play either way at all and even gets stuck if you push it all the way down, which is where most of the carbon buildup is on the rod. These are normal pushrods and are just like any 350 chevy pushrods, so no reason for this tightness.
To reset memory of the head, which I know many of you have seen far more than I have. There is a upper 9/16" hole and a lower 9/16" hole that the pushrod goes through. The rear pushrod has clearly a 9/16" hole up top. But I cannot see down into it yet, but the lower hole seems to be only .01" larger than the pushrod. All the pushrods in the engine does the same thing when I stick them down in the back lifter hole. It's not just that one specific pushrod. They all get stuck.
This is not the original head for this 2.5... The original was cracked 17 times due to the guy that had it had altimers and drove it without water for some time. So this head was bought from a salvage yard and worked over when I rebuilt the engine in 01. What doesn't make sense is that it drove relatively good for 4000 miles then all the sudden that pushrod seizes up in the journal. It feels like the hole is a perfect circle, only that it is barely larger than the pushrod diameter. We are expecting a 12" snow here in NC tomorrow, so I am hesitant to pull the head off yet. Seeing as the SKY is my garage... Anyone heard of anything like this?
 

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Discussion Starter #3
No all the pushrods are just as tight in that one hole. I know the only answer is to pull the head off. I cannot position myself above the hole do just look down inside, but there is no way I'm going to try to just throw a new valve train assembly back in and try it. This is truly dumb as hell, there is no way it has been this tight for 3000 miles now.
 

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Just throwing this out there but may the retainer have come off of that lifter and the push rod seat have come off and possibly be obstructing the push rod? I once had a set of cheap lifters and one came apart on me.
 

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Just throwing this out there but may the retainer have come off of that lifter and the push rod seat have come off and possibly be obstructing the push rod? I once had a set of cheap lifters and one came apart on me.
That is sound advice.

mlnhead: Can you get the tappet inspection cover off to see what the lifter looks like?
 

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That is sound advice.

mlnhead: Can you get the tappet inspection cover off to see what the lifter looks like?
Ya like mlnhead said you should be able to get to the inspection cover off and wont have to pull the head. If it is a lifter make sure you get a good brand lifter. I havent had much luck with house brand lifters

Sent from my HTC U11 using Tapatalk
 

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It's been decades ago , but i recall a situation where one of the intake bolts hit the push rod. One bolt was slightly shorter and went in a specific hole.
 

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Discussion Starter #8
Hoosier Rick, I bet you hit the nail on the head... It didn't seem like there was any different size bolts, but I didn't have my mind on that at the time either. Kinda makes me look like an idiot, sitting here with brand new lifters, pushrods, rocker arm kits, and valve springs.I'm going to use them. I know for a fact that the valve springs sat in one position for 15 years. My only worry is using brand new lifters on a used camshaft...
I have about 10" of snow on the truck as we speak, so I haven't been up to going out in it. Thanks to every one of your posts on this thread. There have been some awesome answers, and good leads to what this issue might be. Gives me some good outlook to what I need to do first...
 

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Boozebag
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Hoosier ...
You NAILED it. You get the cigar. :tup:
The last (second to last?) intake manifold bolt is shorter than the rest. I am fuzzy memory on that one.

Minhead - if you pull that last 2 bolts out, the pushrod will come right out.
I suggest not replacing everything, it's a waste of $$.
These are hard parts that can be returned unless you special ordered them. Even then, they may charge a small re stocking fee.
Make sure that you install the pushrod guides in correct sequence. They are numbered.


If you remove one bolt at a time from the intake, you will find the shorter one. OR... you can cut 1/8" off of the bolt that is in there.


Another suggestion - change the oil and filter. Even though the pushrods are hardened, they may have shredded off some shavings.
Won't hurt to do a change.


Last... GM made 8 (IIRC) different heads for the 2.5. You have to go by the casting number to match your old head.


Since fotobucket blackmailed everyone, all of the pix for my 2.5 head swap are gone. I had to go through contortions to make an Ebay head work on
one of my 2.5s.
I guess if yours is working, then it's ok.
 

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Discussion Starter #10
Yeah, back in 01 when I did this rebuild, the 2.5L heads were still plentiful in the salvage yards, so I actually got a 1992 head of correct casting #'s. There is another story that goes along with what took so long to get this truck on the road. The machine shop that checked the cracked head and reworked the replacement head, somehow stupidly put the cooked valve springs onto the good head. I had given my Dad this truck back then, so he could sell it or what have ya. The compression was all over the charts from 85 lb. up to 135 lb. back down to 85 lb. on 3 cylinders. 1 cylinder was good. As you know there are so many stories about all the Iron Duke and these stove bolt engines about how to prep the lifters and such. Dad and I were puzzled as to what was causing this. It got put on the back burner while I went out of State on my job. Dad tinkered with that issue and a ground issue that was plaguing this truck, for a couple years... He finally happened to think about having the old valve springs in a box, and thought it was worth a shot changing them. Thinking there was a possibility the cooked valve springs had gotten onto the head by stupid chance, and they would most likely have been collapsed. Sure enough the idiot at the machine shop had screwed up. Engine ran much better with the other set. I kinda suspect it was on purpose. For one, he sure didn't check the springs for tension... Dad died back in 2015, so almost all data around my garage died with him. I have so many things he was in the middle of that I have no idea where or what he was working on here. I keep him living on with my AutoZone and Advance warranty system. His phone number will always be what my parts are listed under... Kewel thing is, his old boss freely gives me Dad's Autozone employee discount to this day.
I want to go ahead and change those old valve springs, and the valve stem seals, like I said they sat for 15 years out in the weather. Doesn't smoke but might as well while I got it down this far. Not sure if I trust that roller lifter after it got held in the hole like it did with that intake bolt. Thank you much for your feedback.
 

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Boozebag
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I don't know how long the engine ran with the pushrod stuck like that, but it may have torched the cam or lifter. You can check by removing the bolt and rotating the engine to see if the pushrod goes up and down. If not, pull the lifter and see what's up.
If you can push on the valve springs and the compress easily, you probably have weak springs. They don't usually go bad though.
 

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Discussion Starter #12
It started the click after I had pulled the intake and reinstalled it. I didn't put over 20 miles on it, with seafoam and marvelous mystery oil in it... I gave up and sought some good advice on here. I'm going to go ahead and change the lifters, and all. I know the valve springs sat for 15 years, as well as the valve spring seals, even though they were new...
 

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Discussion Starter #13
It's been decades ago , but i recall a situation where one of the intake bolts hit the push rod. One bolt was slightly shorter and went in a specific hole.
Yep yep, that was it. The back bolt you have to tighten or loosen from the wheel well. You deserve a ribeye for sure...
 

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Do the pushrodsI have to go back in the same order as they came out or does it matter since they are all the same size
 
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