Need Help ATTN 4.0 Guru's No compression after head work

I'm attempting to put my dads 4.0 back together here is a little history.

The vehicle is a 2000 with the 0331 head. It overheated and warped the head. We had the head professionally checked for cracks and the head was determined to be usable. We had the head machined to straighten it out. We are now reassembling the engine and went for the first start of the engine and there is obviosly no compression on the whole engine. The starter will turn the motor over with very little resistance like cranking the motor with no spark plugs installed.

What we have done.

Removed the valve cover and loosened the valve rockers for all valves. With engine disabled cranking of the engine results in the sound of increased compression. When tightening the rockers, all of the valves seem to have been opened a little. 1 of 2 things is going on, the push rods are too long or the machine shop gave me back the wrong rockers.

Here are my questions.

1. are there different length pushrods for engines that have had the head machined.
2. are there differences in the rockers from year to year.
3. is there a way to determine how much material the machine shop removed, i was unable to find that out from them at the time they returned the head to me.

I have done several rebuilds of 4.0's but have never needed to have a head machined because it has been warped. Unfortantly i don't know how much the machine shop took of the head. I have never heard of having to purchase new push rods for this case, but there is a first for everything.

Any help that you can provide is deperately needed.

Thanks in advanced.

For how much has been cut off the head face, when we originally machined heads, we maintained a deck to combustion chamber button depth. They don't tell us that in the FSM, so you would have to depth mic it and compare it to a un(re)cut head. The do tell us that the combustion chamber volume should be 55.22-58.22cc. so you could figure it out from that. If you are too small, you may need to run premium to stop pre-ignition. I never heard of needing shorter pushrods for your problem. I guess you could shim under the rocker arm pivots. Maybe a better answer would be to try to get a thicker head gasket. That would solve compression problem too.

Jeg's and Summit sell adjustable push rods for when you do custom builds. But in my opinion if they removed enough material from the head to make the push rods to long it's to much. Removing that much material will raise the compression ratio without the use of a shim or thick head gasket. I'm sure the specs for the head thickness are out on the net.

Were the valve seats recut too? That would make the valvetrain shorter too.

The valves were not recut.. We are trying to get it back together as inexpensivly as possible. Last night we were able to put a washer that was about .062" thick under the rocker arm bolts. This resulted in the engine running very poorly.

There is obviously a few valves that are loose now with the washer installed and i'm going to use a thinner washer and see if i can get the valve noise out. There is obviously a miss in one of the cylinders too. There was also quite alot of smoke/steam coming from the valve cover vent. This was coming in puffs that were in harmony with the miss.

Here is my new set of questions. The lifters were not replaced and i think they may be nearly fully inflated. It also seems that when i'm tightening the valve rockers that the valve spring will compress before the lifter will. Is there away to correct this?

Also can someone point me to where i could find a thicker head gasket?

Jerms

the rockers arn't on the wrong way are they?

How much was taken off the head to make it flat? The lifters should pump down after a few minutes of running.

Don't use adjustable pushrods.. they are pretty much a bad idea. Summit, Jegs, etc have a shim package for a ford that will work.

You need to check your preload and determine how much you need to shim or the length of new pushrods.

And you still can't see a crack in between the #3 & #4 exhaust valves with all that steam? Sorry, but I'm suspicious of the quality of your "professional" check for cracks. Overheating a head known for cracking enough that it needed machining to make it flat had a good chance to make that crack. Hate to have you chase this valve issue if it's a waste of time.

The machine shop i had do the work has done lots of work for me in the past i belive that they do good work. They did a magnaflux pressure check and determined that the head was usable. I am still trying to dertermine how much they removed from the head. The steam/smoke that i'm seeing i now know is coming from the cam side of the block very close to the middle of the engine. The steam/smoke comes up from the area of the lifters with some pressue. It is also present when cranking the engine with the engine disabled.

I will keep you posted as progess continues.

Thanks all for the help you all have always been very informative.

Jerms

are the pus rode properly seated inside the lifters. maybe it will just take some time for the lifters to re-collapse after reassembly.

Jerms said:

The steam/smoke that i'm seeing i now know is coming from the cam side of the block very close to the middle of the engine. The steam/smoke comes up from the area of the lifters with some pressure. It is also present when cranking the engine with the engine disabled.

Click to expand...

That doesn't sound good.. coolant possibly coming from where the head meets the block? There isn't that much on that side of teh block to leak/smoke.. you have the oil filter, dipstick hole, pressure sensor hole, and distributor hole.

There are a few freeze plugs on the rear of the engine.. Are you sure it isn't electrical related?

my guess is 1 of 2 things are goin on here
1: the machine shop took off too much material which is probably what happened
2: the wrong head gasket # or gasket placement :wierd:

Look on craigslist for a replacement head, not an 0331. I got a '98 head for $50 on craigslist.

I don't think the smoke is electrical as the smoke is coming from the engine internals (area where the push rods come up from the block). I have run the engine for a few seconds with the valve cover removed. I belive that the machine shop did remove too much material. I have done some researching and have been unable to locate a part number for a thicker head gasket. i'm positive that the head gasket is properly placed and oriented correctly. tonight i'm going to attempt to get the rockers shimmed and make sure that we are getting even compression in all cylinders.

Thanks again for the help.

Jerms

So, the smoke is coming from inside and rising up from the block and coming up through the pushrod holes in the head? If so I suggest you loosen the rockers so the valves are closed and do a leak down test. sounds like compression is getting past the pistons. Can you tell what the smoke smells like?

A thicker head gasket will not help your problems. It may correct the pushrod being tool long, but that is the wrong way to correct it.

You are correct the smoke is rising from the holes the pushrods come through, We may be loosing compression past the rings in some cylinders. I'm going to attempt to determine which cylinders are the problems.

are you sure the gasket was put on correctly, with the coolant passages open at the rear of the engine

There is news...

We were able to get the valves shimmed correctly so that there was proper lash. However there is still a significant miss.

We performed an engine hot compression test. There is bad news, cylinders i and two are fairly low.

1: 30 PSI
2: 60 PSI
3: 110 PSI
4: 105 PSI
5: 120 PSI
6: Not tested. (unable to get comperession tester in the cylinder)

We determined the front 2 cylinders are leaking by the valves. So we loosened the rocker arms up some more to ensure the valves are closing. No change in leakage. So the head is coming back off. Here are some new concerns.

If we take the head back in to have the valves and seats ground, can the machine shop also shorten the valve stems to correct for the need of shims?

Is it possible for a head to warp to the point where the valve seat is no longer round?

again i appreciate all of the help you all have been...

Jerms

How much did you have to shim the rockers to get they to proper preload? It really sounds like your head has a lot of problems and is probably not worth fixing. I wouldn't use it now. Find a good salvage head and have the machine shop go over it... I would try to get them to do it for free since they screwed up the last work they did for you. If not, find another machine shop.

Now, what about the smoke coming up from the block?

You can get bluing to put on the valve seats to see how they contact the valve. You can also set the head upside down and put alchohol, gas, water, whatever liquid, in the chamber to see if it leaks out. Number the valves before you pull them. You can also seat them yourself with valve grinding compound but be careful to not get them too wide. If you grind the ends of the valves, you will need to take off twice as much as the shims you needed. Do your cylinder walls look OK?