Head Gasket replacement problem ....

[Knightgang]

Re: Head Gasket replacement problem ....

I agree with other here, oil comming out of hte valve cover valves is due to excess crankcase pressure. This is caused from the blowby, which is due to a bad compression ring allowing the pressure from the compression stroke to escape the cylinder and into the crankcase...

Headgasket replacement will not fix this. You need new rings. Might be time for a rebuild...

 

[JustJason]

Re: Head Gasket replacement problem ....

don .... on the adjustment .... I tightened bolt while feeling play ... kept tightening until no play

You have to define "play", as everyones "feel" for things is different.

The way I do it is like this
With 1 hand, using just my thumb and 2 fingers, is a roll the pushrod back and forth. At the same time, start to tighten down on the rocker nut. As soon as you start to feel the pushrod dragging in your fingertips, this is 0 lash. Then tighten down as nessecary according to the procedure in the book, but do it in small increments. For example, if the book calls for 1 full turn after 0 lash, find 0 lash, then do a 1/4 turn, wait 30 seconds, do another 1/4 turn, wait 30 seconds, etc etc...

Remeber, 0 lash is a light drag on the pushrod when rolling it with a thumb an 2 fingertips.

 

[Fishermark]

Re: Head Gasket replacement problem ....

You have to define "play", as everyones "feel" for things is different.

I agree that it can be a very subtle thing - In addition to rotating the push rod between the thumb and finger, I keep moving it up and down and pay attention as that movement keeps getting smaller. Then you know when you are getting close.

Then tighten down as nessecary according to the procedure in the book, but do it in small increments. For example, if the book calls for 1 full turn after 0 lash, find 0 lash, then do a 1/4 turn, wait 30 seconds, do another 1/4 turn, wait 30 seconds, etc etc...

Jason - why do you do that? I can see doing it that way if you are doing it with the engine running, but not with a static adjustment.

 

[Silvertip]

Re: Head Gasket replacement problem ....

#1 on the compression stroke is very easy to identify with the valve cover off. Both valves are closed since the valve end of the rockers will be fully up. Remember - the TDC timing mark comes around twice to complete a power stroke on a four stroke engine. While the timing mark may be on TDC, it is on TDC for the "exhaust" stroke in which case an exhaust valve would be open. If you adjusted the valve at that setting you not only risk a valve and piston collision, it would also account for no compression.

 

[JustJason]

Re: Head Gasket replacement problem ....

Jason - why do you do that? I can see doing it that way if you are doing it with the engine running, but not with a static adjustment.

If you force the pushrod down to quickly you take the chance of blowing the oil out of the lifter. It may not happen every time, but you run the risk of it by tightening down to fast. If you blow the oil out, it's going to feel like you haven't even reached 0 lash yet. And if that happens your going to keep cranking on the nut until the pushrod "feels" tight. When you go to start the engine back up, the lifter will re-prime with the new oil pressure and the valves will be way to tight, and they will not close.

There is supposed to be a little bit of play in the valve train. Not to sloppy, but not to tight either. I think that's what throws people off... that there is in fact supposed to be a tiny bit of slop. After the the engine is up and running again, oil pressure negates that slop. People need to think about it like this; It is ultimately moreso oil pressure that opens and closes the valves, and not the pushrods or the rockers.

The lifter has some travel inside of it. Under the pocket that the pushrod sits on that you see from the outside, Is a hollow cavity. That cavity gets filled with oil pressure when the engine is running. What your trying to do is push that pocket down, to the middle of it's travel. When the engine is running, oil pressure pushes that pocket back up.
If the pocket is initially set to low, oil pressure with push the pocket ALL the way back up, and will keep the valve from closing. It would be like making a pushrod 1 inch longer than it's supposed to be.
If the pocket is set to high, oil pressure pressure will still push the pocket up, but because the rocker arms position is higher than it's supposed to be (by not tightening it down and compressing the lifter) the valves will close just fine, but they will not open all the way. It would be the same thing as having a pushrod that's an inch to short.
It would make more sense if it was called a "lifter pocket adjustment" instead of a "valve adjustment". Because in the litteral sense, your adjusting the depth of the lifter pocket.
Good splaination??

 

[Silvertip]

Re: Head Gasket replacement problem ....

Close description but still not totally accurate. A hydraulic lifter consists of an outer body that rides up and down on the camshaft. The lifter body has a plunger inside it so the entire assembly may be thought of as an upside down cylinder with a piston inside it. The push rod sits on the plunger. The cavity between the plunger and lifter body is filled with oil under pressure from the oil gallery. You statement about the valve system must have some lash is not correct. The object of using hydraulic lifters is to eliminate this slack entirely. Now here is where the adjustment business gets confusing and to your credit you did touch on it. For proper lifter operation the plunger has a given range within the lifter body in which it can operate properly. Adjusting the rocker arm nut is the only adjustment in the entire system so it is what determines "where" inside the lifter that plunger sits. With the engine running, a hole in the side of the lifter body allows oil pressure into the lifter to push the plunger upward to close up any slop in the system IF IT EXISTS. Oil pressure does not operate the valves. When the lifter BODY gets to a specific spot in the engine block, the oil pressure hole is blocked, thus trapping the oil in the lifter body. Since oil (most liquids in fact) do not compress, the lash-free situation exists and the lifter is now acting like a solid lifter. Many engines today have no lifter adjustment as tighter manufacturing tolerances are all taken into account and the rocker arms can simply bolted down which puts the lifter plunger in the correct range. Overhead cam motors use hydraulic lifters as well and generally no adjustment is provided. Just in case many of you use Wikopedia as a source of reference, a quick check out there indicated "cars in the 1980's were designed with hydraulic lifters." Good heavens, GM was using hydraulic lifter in their overhead valve engines beginning in the late 40's. Even the automatic tranny equipped Chevy sixes in 1950 had hydraulic lifters. The hydraulic lifter is one of the reasons full flow oil filters became standard.

 

[peterg000]

Re: Head Gasket replacement problem ....

Ok .... here is the update .....

Valves where to tight ..... everyone was dead on with the valve adjustment being the issue with no compression & no engine start after my head gasket replacement. I re-adjusted the valves according to all suggestions, and even though never felt comfortable with adjustment being 100% on, started up the engine and what do you know ... it started .... didnt sound to bad either. Now back to the adjustment ..... how can anyone know exactly that they have adjusted right .... my feel for when it starts to drag is different from someone elses ... also, if one rod has more oil on it than the other, wouldnt the drag be less causing you to tighten the bolt even more?? does anyone have a more definitive way to make sure valves are adjusted right?

Thanks again all for pointing me to the valve adjustment!!

Glenn

 

[Bondo]

Re: Head Gasket replacement problem ....

I re-adjusted the valves according to all suggestions, and even though never felt comfortable with adjustment being 100% on, started up the engine and what do you know ... it started .... didnt sound to bad either. Now back to the adjustment .....

Ayuh,... Now that it's Runnin',.. You can run the valves the Easy way...

Start the motor,+ run it about 1000rpms for 2 or 3 minutes to warm it abit....
Take the valve cover back off,...
Start the motor to idle...
With your wrench, loosen the 1st valve adjusting nut til it starts to Clatter,...
Tighten til it goes Silent,... Then 3/4 turn more...
Then on to valve #2, repeat, #3, repeat, etc....
When done, reinstall the valve cover,...
There'll be abit of spilt oil, but wipe it up....
You're Done...

 

[peterg000]

Re: Head Gasket replacement problem ....

Bondo ...... sounds like a plan ... love it .... nice and easy. Will tackle this on friday and let you know how it went.

Thanks again ....

Glenn

 

[JustJason]

Re: Head Gasket replacement problem ....

You statement about the valve system must have some lash is not correct

What I had meant by that was on a cold engine, one that needed an adjustment. When setting lash it will appear first as being sloppy. As PeterG000 found out, and most DIY engines I see. The valves were way to tight because they either don't understand the procedure or don't understand what 0 lash actually is. So what I tell people is that when you first set them (before the crankdown on the nut) Is that it will appear to have slop. Which is why later I wrote...

After the the engine is up and running again, oil pressure negates that slop.

Oh well, either poor writing or poor choice of words on my part.

how can anyone know exactly that they have adjusted right .... my feel for when it starts to drag is different from someone elses

Think about whats causing the drag first. If the rocker arms are loose. The pushrod is just floating there. As you tighten the nut down while rolling the pushrod at the same time. You will feel a point in which the rocker arm is pushing down on the pushrod, against the plunger(or pocket, if you want to think of it that way), creating resistance to your rolling. It's slight, but as soon as you feel the drag,(or resistance to rolling) that is 0 lash. The pushrod will still roll, it just takes an ounce of extra effort to roll it.

If your all worried about setting it correctly. Do a compression check on all your cylinders and note it down. Perform the procedure the best you can. Re-do the comp check, if your compression goes down by even a few psi, the valves are to tight. If your compression happens to go up from the initial reading, that's because the valves were to tight to start with on the first test.
If compression doesn't change, and if the rocker arms aren't rattleing at any rpm, then generally you have it set correctly.

BTW... I prefer shim over bucket... takes the guess work out of things

 

[peterg000]

Re: Head Gasket replacement problem ....

Update .....
Valves adjusted and everything looks good. Engine runs pretty good. Put a new temp sensor in with Thermostat .... there wasnt a Thermostat in when I opened up. Took boat out on the river out for a little bit of a stress test and then after about 15 20 minutes temp rises and overheats .... also alot of steam coming out of valve on valve cover ... very steady. Didnt get a chance to go back and check everything out as far a cyl pressure ... will have to do that another weekend. any idea why overheating to a point where steam coming out valve on valve gasket? .... Replaced Impeller, replaced thermostat ..... what else could it be?????

Glenn

 

[Don S]

Re: Head Gasket replacement problem ....

What's the condition of the manifold and riser. if they are plugged up from rust and corrosion, the best pump and thermostats in the world aren't going to help.

 

[peterg000]

Re: Head Gasket replacement problem ....

Don ..... not realy sure the difference between manifold and riser, but manifold looked ok .... how would I check to see if ok?

Glenn

 

[Don S]

Re: Head Gasket replacement problem ....

You can just look at the manifold and risers and see if the water ports are open between the manifold and riser.
I have the water ports kind of marked out in the picture below. There are also openings in the riser near where the exhaust hose attaches to the riser. If they are plugged up, then water can't get out. Too much restriction and it slowly or quickly overheats.

 

[peterg000]

Re: Head Gasket replacement problem ....

Don ..... Pictures work for me!!!! Now I know what the heck a riser is .... didnt say in the seloc manual I have. I will check them out this weekend. If clogged up a bit, would that be causing all the steam out the valve on the valve cover?

Glenn

 

[peterg000]

Re: Head Gasket replacement problem ....

Update ....

Just wanted to update on the riser replacement and the temp issue .... riser seems to have taken care of .... temperature steady so far. Still getting steam out the valve cover breather .... will open a new thread to discuss that issue ...


Thanks all for helping with this one ....

Glenn