Me again.. The guy that ALWAYS experiences the WEIRDEST problems as it relates to LS engines. Working on my daughters truck today. 5.3 LS, that cracked the #5 exhaust port wall between a water jacket and was pushing coolant straight out the exhaust. Back today working on it. Picked up a set of 862 heads from a machine shop on Saturday. Story goes they are completely re-worked-valve job, new valve guide seals, hot tanked, surfaced. They look AWESOME.. However... after getting them both bolted on I went to put the rockers and pushrods in (factory length push rods-stock LM7 cam) and I find that as I was initially running the rocker bolts in I find that the push rods seem to be too long... as in EVERY valve on the one head was opening as I started to tighten the rocker arm bolts... I then put cylinder #2 in a position where the EXHAUST valve was just starting to open-meaning the intake valve should have been CLOSED and on the HEEL of the cam... When I tighten that intake rocker arm down to 23 lb. ft. the valve is clearly being held open! You can watch the valve spring compress as you are approaching the 23 lb. ft. This is an ALL STOCK set up. Factory cam, aftermarket head gasket (.051" compressed thickness)... Why the heck are the push rods so long? Is it possible the place I bought the heads put the wrong valves in and the installed height is just way too high? Did they mill an excessive amount off the heads causing this now too long of a push rod situation?

I have a set of 7.300" push rods here so I decided to try one of those.. Doing the "turn method' they bring me right up to the 1 full turn to hit the 23lb. ft. torque spec-but still you can see the valve is opening as you approach the 1 full turn! When I used the factory push rod and did the turn method-it's coming up to over 2.5 turns before it gets to the 23 lb. ft. torque spec and clearly the valve is being pushed off the seat before you hit the torque spec. I'm suspecting something is up with these heads.. I just can't quite put my finger on it. BOTH push rods-factory length 7.400" and a 7.300" are lifting the valves off the seat/compressing the valve springs on ALL valves on that bank-all 8 of them. Is it possible they put the wrong length valves in the head? What other things could cause this situation. Keep in mind I did NOT remove the lifter trays, or lifters. All of that stuff should still be riding directly on the cam as NONE of that stuff was disturbed. I'm pulling out my freaking hair trying to figure out what is happening here. If anybody has a suggestion as to what to do next. I don't want to keep working on it and put it all back together only to realize that the heads have to come back off.. This is causing me great stress as you can imagine. I thought I could just put this engine back together and get it down the road. Now, it's turning into a **** show. I think I'm going to pull one of the heads back off, and put another old 706 head I have here on the engine, just lightly bolt it down with an old head gasket, and then put one rocker and one factory length push rod in place and see where that puts me.. If another head puts the rocker arm geometry back in-line, then I know something is desperately wrong with the heads I just bought..

If anyone has any ideas.. Please advise. I'm about to drink a beer and call it a day at 11AM in the morning.

 

Well, Being that you got the heads from a machine shop...did they say what they did to them? It sounds like there is a mixture of milling the heads quite a bit and/or probably cut the seats too deep for the valve job. It's really hard to say without being able to measure. All we can do is give suggestions. You need to get the shop to give you exact specs. If they're a shop worth anything, they'll have all the tools needed to measure it all.

 

I called the shop. They are willing to make it right. I'm going back to exchange them tomorrow. I pulled one of these heads and put an old 706 head on. I then put 2 rockers on along with the rocker stand-and the factory length push rods are perfect. Valves are not being lifted off the seats. In looking at the new head that I just picked up from the machine shop, compared to the old head sitting right beside it.. It looks like the valves are taller/higher as I tried to measure up from the flat rail where the valve cover gasket sits. Not scientific measurement, but repeatable going back and forth between the heads. The valves are NEW in these heads so maybe china valves that are not the correct length. I'm also certain that the installed height was not checked as the valve springs are super soft. As in I can push down on the retainers with just 2 fingers and compress the springs a little bit before they suddenly get firmer. Like they are not being compressed enough at the point where the valves are seated. I also realized when I was bolting down the rockers and could see the valve opening that it should have taken more force with the rocker bolt to be forcing the valves open.. But using a hand ratchet that is 8" long at best, and turning the rocker bolt, it was easily unseating the valves and leaving them hanging open. Just one more "F you!" from the universe. But, if life were easy I would not be as "experienced" as I am right? The upside, I get a brand new opportunity to finish tomorrow what I started last week. I'm really not upset about this. I'm just glad I figured it out before I bolted up the headers, and P/S and A/C and Intake, and all that other jazz... Live, learn, love what you are doing!

 

Did anyone mess with the cam/gears/valve timing? Just curious, as the cam could be installed wrong. I don't think this is the case, but thought I'd mention it. Even if it was installed wrong, you should still have some valves closed. Hmmmm-were lifters changed, and possibly taller than stock were installed? If nothing has been disturbed since it ran, perhaps longer than stock valves? First call should be to the machine shop, I'd say. Best of luck to you, sounds like you're due for some!!

 

Nothing else touched on the motor except the heads were pulled.

 

Are you sure you had the rocker stands on the 862 heads?

 

Yes, absolutely sure the rocker stands were in place. I had to de-sludge the rocker stands before installing them. They were wire wheel cleaned to get all the sludge off and they were in place on the new 862 heads before I put the rockers on. I know this because I have to put the rockers at either end-farthest at the outter ends -to hold the stands in place. That was not the issue. There is something else drastically wrong with the valve stem heights that is throwing off the geometry. I will have it resolved tomorrow. For sure. The spare 706 head I have here proved to me that this was an installed height on the valve stems.. Nothing else it could be.

 

Sure looks like you've found the problem. I'd like to know who didn't do their job, here. The stem tip to valve seat surface length must be way too long!! Damn lucky you looked it over!! I once saw "daylight" where there shouldn't have been any, namely between the valve seat and the valve!!! I had hardened seats put in some old SBC 2.02 camel hump heads. They did a good job on everything......except 1 intake valve!!! I was rolling the head around on the bench, and all of a sudden, I see my bench worklight shining where it shouldn't have. Glad I caught it before the install!!!

 

Just an upate.. Got a 2nd set of heads from them and they went on without issue. I did not wait around for him to check out the 1st set of heads. I just did the exchange and left. He is a good guy, and did stand behind his work, so I will use them again. 2nd set of heads went on without issue and the engine is up and running. Now, I'm fighting getting my O2 sensors to work. Truck had codes for INACTIVITY both banks before I did the engine work. Put 2 brand new sensors in, and scanning it with HP Tuners shows NO O2 activity. So... I know for sure they worked at one time.. unless the wiring has gotten damaged to BOTH sensors... OR, both new sensors are bad right out of the box. Or, the computer is bad... I have to figure this out now.

 

Got both O2 sensors back on-line and reading. Fuel trims were way off as a result of the engine coolant passing by the O2's.. I drove around and after just a few minutes of driving I watched on my scanner the vehicle go into closed loop, and then the fuel trims started correcting. Long terms were +25 on BOTH banks... but slowly came down to between 3/5 +/- after driving for about 15 minutes. Truck is STALLING when I come to a stop. I'm having to lightly pedal it to keep it running. Fuel trims are in-line now so I believe the IAC is no good. I will replace that tomorrow and see where she falls. Right now it's like the IAC is not even trying to catch the slowly falling engine RPM.. The RPM just slowly decreases until the engine stalls. It's set to idle at 550 and has worked there for years. No reason it should not work there now. My history with IAC's is that they can cause you to do some crazy things like chasing your tail.. Questioning your tune... Wanting to take a Ford tool (hammer) to the vehicle just to relieve some stress.

 

Just to finalize this post... What do you guys thing was the final issue??




To summarize... Every time I shut the truck off, and then re-strarted it it would run fine for the first 3 minutes, and then go to pure "S" for the next 7 minutes, and then run normally after that.... EVERY time I started it up... What do you think the real issue was?




For those of you who guessed a loss of power to the PCM after the key was off-give yourself a cookie! I have a cheapie-CHINA MADE TRASH-after-market wiring harness on this truck . Essentially the fuse for 12V+ power supply with the key OFF was popped. So, memory was being LOST each time the truck was shut off.. Every time you turned the ignition off, EVERYTHING was lost... I finally realized that... something must be wrong with memory because each time I start it and start to drive it, it seems like it has to relearn EVERYTHING in order to run correclty... Then... I thought.... Wait.... check the fuses in the AFTER-MARKET..... CHINA MADE..... stand alone wiring harness... low and behold.. I find a fuse for "MEM" blown... I replaced the fuse and after driving it a short while, shutting it off, and re-starting it... it has retained memory and is running like a champ. 2 things I've learned from this;
1. Recognize that if the vehicle is having to "relearn" after every key start-you might have a memory problem.
2. If the tune on your vehicle is so terrible that it has to "relearn" when you change the battery, or disconnect the battery, or the PCM loses memory-you have a TUNE issue.

Now that I have found the REAL problem.. I will tune it better so that even if the memory is lost, the VE table, and MAF table, will be spot-on, and the truck will still run perfectly., Did I mention that the OBD2 port has a short, or loose connection such that if you don't hold the connector tightly against the port that it keeps losing connection? Yep... cannot scan it while driving, or flash the PCM, unless you are holding the connector at an odd angle to the right side of the port otherwise you risk the "LOSS OF COMMUNICATION" message.. Yes... I've ordered a NEW OBD2 port for mounting under the hood that I will use going forward. But.... for now..... I WON! F YOU electrical problems! I WON!!!!!!!! I'll mount a new OBD2 port under the hood, and tune it to perfection... and I... and I alone... Will be the master of my problems again! HA!

 

Great informative post KB! Thanks for the report.