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25lb pounds cyl #4

J

jsaylor

New member
While on a road trip heard slight ticking then mostly went away, left me with a rough running engine, service engine soon flashing, checked compression all ok except #4 at 25lb, I tested this cyl 10 times twice it pumped to 100 lb. 3.8 supercharged have owned and cared for since it had 58k now has 110k 2001 buick 3.8 supercharged.
 


I would guess this is a severely cracked head. The cracks show up between the intake and exhaust valves... I have fixed more than 1 3800 with this problem.
 
Where do I listen 1) ? 2) exhaust I assume tailpipe 3) would I open the oil filler cap and listen. not certain where to listen on intake.
Thanks for your help.
 
You know that likely the head needs to come off. Start with the valve cover and if you see a broken spring..replace it. Likely that'll give you full compression again. If not.. let us know when you get the head off, what you find
 


I don't know if this will help any, but I would get a flexible funnel (like a transmission funnel) and put the end of it in the spark plug hole. Pour a couple ounces of transmission fluid into the dead cyl. Replace the spark plug, cycle the motor BY HAND a couple revolutions, let it sit a little while and cycle it again. Do this a couple times, let it sit over night. Next day, remove plug, cycle again a couple time without the plug installed to spit out the puddled transmission fluid. Check compression again and see if the changed anything. If you test it 10 times again throughout the day and it never drops below 100 then run with it. If it changes nothing then it's in the head.

I was experiencing a similar problem and this fixed mine. My UIM gaskets blew and washed out the cyl. I did this to my motor and it's ran fine since. Situation is different, but worth a shot.
 
Thanks so much for your help, I was pulling the valve cover last night and quit, it looks to me you have to pull the alternator and tensioner, I will inspect the rockers and springs this evening. I will then try adding the atf as mentioned, is this for rings?
Thanks
 
It's a lot easier to pull the rear valve cover with all that out of the way. I'd purchase new coolant elbows to replace your existing ones that you will pull out with the tensioner.

Others can comment, but you might want to try the ATF trick before you go through all that.... Just my $.02

And yes the ATF is to help the rings "reseat"
 
Ok pulled off the back valve cover to find the number 4 intake rocker as loose as could be, removed the rocker and the push rod is sunk down almost to where It's hard to reach. Push rod moves easily, how is it you have little to no compression if the valve does not open? does this mean a collapsed lifter?
any other way to repair without removing the intake? do the heads have to be pulled?
Thanks
 


Removed the push rod, broken in half just barely holding on, do I just replace or is there usually a cause? thinking of picking up another at napa, do they have different size rods for 2001? or for supercharged
 
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You'll be lucky if the lobe on the cam isn't damaged.
It could have just been a defective rod...it happens.

Have you been running the engine at high rpm a lot? Valve float can be hell on parts.
 
Don't drive it hard at all, was on a 10 hr trip in 105 degree temp, I have never had the temp gauge go over half way since I've owned the car the last 6 years, I did drive the car about 300 miles with the ticking noise, as mangeled as the push rod is there are no signs of wear on either end of the push rod and no sign of damage on the rocker.
Thanks
 


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