never ever ever brag... compression?'s

[p24-1953]

Well just a few days ago I got on here and stated how happy I was and how good the car drove. Then this morning I hoped in the car with the family and started off to church. It was running great... after a few blocks I stoped at a light and pushed in the choke all the way. after the light the car ran like cra...well you know. After a few block it got even worse. It would idle okay, rough but okay... when you put a load on it the whole car shuddred, but it stilled moved and ran. After church we limped home and up the hills of death. When you got going in gear it wasnt bad it, rode rough but wanst shaking. If floored it toped out a 30 in 3rd. After it cooled down i pulled the plugs and noticed a few were dark. decided to run a compression test....

2 months ago my compression was 110-115 on all 6 cylinders.

Today... 115, 115, 0, 0, 40, 35

What happened? blown head gasket? i wasnt burning oil or smoking. Stuck valves possibly? There was no noticble sound of knocking.

what is amazing is it drove home.. these engines are built like a tank.

[jd52cranbrook]

Pretty easy and quick to pull the head and know for sure. My bet is a gasket.

[P-12 Tommy]

jd52's probably right. Head gasket most likely blown between 3 and 4.

Tom

[Plymouthy Adams]

never grab a snake by the tail..and the longer the snake the more this should apply...bite you in the butt every time..sorry to hear this...quick removal of the head will more than not reaveal the prob..give you a chance to survey the inner works while in there, valves, seats, piston top for signs of detonation...be sure to reomve the head in proper sequence..while you have it off..have it checked for warpage..if needs be ground flat..take only as much as needed to repair the warp..don't be tempted to go high compression with a full cut...save the metal for future problem resolving..

keep it stock..keep it running

[captden29]

to make what could be a long post short, i will just say head gasket. my past experience with this problem says, like others posting, HEAD GASKET. and yes, mill it as little as possible. i have done head gaskets without any milling and never had a problem, but have the head checked for warpage and milled as necessary and you will only have to do the job once. it really is a very easy job, takes longer to put back together than taking it off. new headbolts are a good idea, about $1 each. capt den

[p24-1953]

do i have to drain the coolant completly to remove the head?

[james49ply]

yes, would be a good idea, did that with mine, don't want any coolent into the oil pan. I drained at the block drain at the bottom of the left side of block near the filler tube and distributor. re-use the coolant then. Head gasket is a simple job, takes a couple of hours thats all. lots easier than overhead valve engine.

[p24-1953]

do the head bolts typicaly come out easily, or are they like the exhaust manifold bolts?

[dezeldoc]

Before going to all that it just might be a stuck valve, when your plugs are out, take a flashlight and look down the hole you will see the intake valve, have someone turn the motor over and see if it is going up and down. I had mine running great and shut it off and came back the next day and it was coughing out the carbs. pulled the plugs and ran a compression check and 75 0 150 0 150 0 now when i ran the check a few months back they all were 150 straight across. come to find out this new fuel does not like to mix with the old fuel and it turns to black goo that sticks to everything. shot carb cleaner through the ports and through the plug holes into the valve pocket let it sit a few hours and they started to free up. put another 10 gals of new gas in the tank and a can of berrymans and now she is back to running great. this is the 3 motor i have seen this happen to, the first one we had no idea what the black goo was, but had to hammer out the valve as it was in there for good! the second one was weird as it was driven all the time then parked for 2 months and it happened. mine had nothing in the tank when i put 3 gal in it when i was first starting it but the new gas loosened up the residue in the tank and sent it all through the system, it took 175 psi of air pressure to get the fuel line to flow again! now anything with old gas is gettin flushed out!

[Jerry Roberts]

do i have to drain the coolant completly to remove the head?

If you have stuck valves you might not have to pull the head . If you do pull the head , drain the coolant completely as your remaining coolant probably became acidic from exhaust gases . Do not reuse the coolant .

[jd52cranbrook]

I would do the oil too. If a blown gasket then water has gotten into the cylinders, which in turn water passes past the rings into the crankcase.

Its a good rule of thumb to save head aches latter.

Also, make sure you have a good torque wrench.

[p24-1953]

well pulled the head in about 45 mins, pretty easy job. i found that the head gasket was split in one location, but would this cause the next bank of cylinders to drop in pressure?

it looks like i have fair amount of carbon on some cylinders, should i wire brush it off? or leave it alone?

why arnt all cylinders equaly black?

I can feel no scoring or wear in the cylinder walls so i guess thats good.

Edited August 23, 2010 by p24-1953

[greg g]

looks a little like the valve next to the cylinder where the gasket blew is not closing all the way. That may be effecting total compression in that cylinder.

[jd52cranbrook]

Next time you drain your water, drain it out of the block too. If the petcock is plugged, now would be a good time to put in a good one with a nice handle to make it easy for the next time. If you have to, extend it out with a 1/8 inch pipe. You best do the oil for sure. And to be honest, that's looks like too much build up to me. But it could just be the picture.

Edited August 24, 2010 by jd52cranbrook

[jd52cranbrook]

Also, the gasket probably let loose because of head not torqued correctly. Or way too hot at one time. If so, yes the gasket on the other cylinders, even though look OK, could be weak too, which would show a drop in compression.

[Young Ed]

Are the cleaner pistons the ones that were by the break? The burning off of the coolant cleans the pistons/

[jd52cranbrook]

Just a FYI. If you can see past the oil film from my front cover oil leak, lol. Here is my shutoff for the block water. 1/4 turn. Very handy. Have one on the radiator too.

[p24-1953]

yep the clean ones are the ones at the blown head gasket.. i think all the valves are sealing well... that might just be an illusion in the photo. I dont have a drain valve in the block. (only a rounded off nub where one is supposed to be... which i honestly didnt do) should i wire brush off the carbon? or will that do more damage than good? is that an abnormal amount for 15 years?

[p24-1953]

Just a FYI. If you can see past the oil film from my front cover oil leak, lol. Here is my shutoff for the block water. 1/4 turn. Very handy. Have one on the radiator too.

what the ruber hose for?

[jd52cranbrook]

That's the inlet hose from my pre oiler. Here is a older pic of it.

But I was pointing to the petcock, I attached a little copper tube to run it down as to not hit anything else. Believe it or not my engine bay was very clean at one time. Will fix it up again this winter.

Edited August 24, 2010 by jd52cranbrook