Anyone who has ever changed HG's. Assistance is need quickly.

91BLOWNSC

Registered User
Anyone who has ever changed HG's. Pistons 1 & 4 do not reach top of cylinder.

Alright, getting ready to put back on the head gaskets and I noticed something about the cylinders #1 and number #4 (both of the front cylinders). As we turn the crank..and the piston reaches TDC, it doesn't quiet go all the way to the top. It seems that the others ones do (the rest of the pistons that is), but the front ones do not. MY dad considered this to be a possibility of a bent rod(s). Has anyone else seen or noticed this when replacing the head gaskets? Why is this? Is this normal or am I in trouble. I was hoping to get most of this put back together today so any help quickly is appreciated!! Thanks!!!
 
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Nope...

I cannot push them down at all. The pistons still fit tightly in the cylinder. It seems the only problem is they don't quiet go all the way to the top. Theres just a SLIGHT edge around the top of the block when those 2 pistons are at TDC that the otheres dont' have :(
 
Ive seen that on a few 4.6l cars bout not on a 3.8l, sounds like bent rods to me.
Do these two pistons look cleaner then the rest?
 
hmm..

One of them is very clean actually. Which means it was probably burning coolant. But the other wasn't (not sure actually, will have to check). And what really throws me is that BOTH of them are IDENTICAL in there gap. Its not like they both have different gaps. There both the same. Which says maybe it was factory. Would you still think it is a bent rod?
 
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Mark,

Each piston should travel the same distance. To make sure your correct about two of the pistons not coming all the way up, get a flat edge to lay across the cylinder and something to measure the distance with. Make sure to remove any carbon buildup from the piston before measuring.

If the cylinders in question are more than a few thousands of an inch lower than the others, the rods are bent. This could happen if too much water got into the cylinder when the head gasket blew.

If they are bent, you should plan on pulling the engine to replace them or just do a complete rebuild. Several people around here have stock rods they will sell cheap. I believe Chris Wise has a bunch of them.

David
 
alright...

Well, that is exactly what my dad had told me. The only thing is, inside the cylinder block, where the piston stops its travel upwards, there is that small black ring you get where the pistons are no longer rubbing on the cylinders (for the last say, 1/4 of an inch before the top of the block), we measured this, and found out that both those front cylinders had a measurment of about 1 millimeter larger than those of the rest of the cylinders. So woudn't this be an accurate assumption that my engine has been like this for a while? I would think that it is an very accurate way in which to check. Thanks for your help and it is very appreciated!!

Edit: For more clearification of info, I was told to add that there is a 1mm differece in the side of the "carbon" track at the top of the cylinders. Thats what I was basically trying to say but didn't have the correct terminology.
 
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Mark,

The carbon remaining on the cylinder wall is from the location of the first piston ring and yes if the carbon is there it has been this way for awhile. It is possible to have pistons in those two cylinders that have the rings located slightly lower. They may be aftermarket pistons that were installed on a rebuild before you got the car.

I would still measure the tops of the pistons. If they are 1mm lower too, the rods are bent.

David
 
well...

Damnit that really gets me. I am only 19 and don't have an excessive amount of money. The car only has 125k on the damn thing. Were thinking about just putting the car back together. I just can't face reality. I mean the fact that both of those have the same size carbon track, and the same piston to deck hieght. It doesn't seem possible both of them would bend the EXACT same way. Thats what erks me. And I did measure like you told me and they are 1 mm off. What if the rods were bent slightly. What would this mean for the engine? performance? longevity? My dad said he beleives those are the stock production pistons in there and that they have most likely been that way for a while (even tho they should be the same as all other pistons) so hes all for putting it back together.
 
Was there any coolant in the oil? If not then coolant didn't mix with the oil and ruin a main bearing. You most likely blew one gasket probably the pass side. Which side blew? If you only blew one side then it's impossible that you hydrolocked both #1 and #4 and bent the rods. Now maybe previuos owner used NOS or it had some work done to #1 and #4 who knows. If money is tight just button back up. Worst case is that you will have to tear back down and do a rebuild. If you develop any bad knocks then you will have to tear down the engine. You don't want to harm the crank as it's not easy to locate a good one. You might luck out and get another few years out of the car. By then you will probably have more money and want a different car or want to restore the SC.
 
yeah....

Only one side went. Though the other side looked as if it started to go. My dad also recommends buttoning it back up. There definitely was no NOS run on this. The engine has been completely stock as far as I know. And the thing is, as far as i can see, the head gaskets are originial. The guy before said he never replaced it and he had it since it had like 50,000 miles on it. I doubt they were replace before that. So if I do end up having bent rod(s) will it knock when i get it restarted? I mean seriously, I do not get this, what are the possibilities. I doubt both of them hydrostatically locked and how would they BOTH be 1mm from the top. Its not like there different, its like they came from factory like that. I know the one piston was pretty dirty still so i know it wasn't burning any coolant. So pretty much my only 3 options are: I have 2 bent rods, the engine had some work done, or a defect from factory? I don't even know if that ones possible. THis is driving me crazy. (still)

Oh and another thing.......no there was no coolant in the oil. Never made it that far.
 
this is interesting... take a look at the 1/4 mile MPH compared to the mods. hes running at like 94mph and not very many mods at all. Maybe this is somthing to do with "factory freaks"? i am probably on crack but i think its somthing to consider.
 
Whatever the issue is, it's not right. Bent rods? Perhaps. Factory Freak? Perhaps.

But what you have is a 6 cylinder motor with 2 odd cylinders. Short cash, button it back up and hope it is a freak and not something more serious.

If you have cash, rebuild the motor. Especially if you plan on bolting more stuff on for more power.
 
decking

maybe this be a reason they would deck the block and align bore the crank mains ..if you got bent rods and been driving that way awhile ..you should have 2 grooves known as the "ridge" created by the rings ..since they don't travel all the way to the top of the cyclinder on the block
 
hmm..

Well thats the thing, there IS a small ridge, but not 2, theres only 1. Each cylinder has only 1. I thought of that too. How long does that carbon ring around the top take to form? If it takes a while, then my engine has been like that for quite some time.
 
Like me and no money? Button it up best you can, take it easy and save your loot. Maybe a salvage yard around your area can get you a good core and you can bolt the your heads to it. maybe ask Pop for a small loan...Just thinking out loud....:)0) good luck!
 
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