Rebuilding the 99 Yukon because of head gasket. Help!

[hotrdd]

So I have done a bunch of investigation. Pressure tests, leak downs and also chased the coolant dye around the engine and it has been confirmed that I have the start of a head gasket failure. I am slowly taking coolant into cylinder #3 which also had a compression of 130. So after going back and forth a few times I’ve decided to pull the engine apart and repair it. I looked into a crate motor but as long as my heads are good I think the best option for me is to just do a rebuild. A month ago I did new Cat’s, O2 sensors, plugs, Idle Air Control Valve and the MPFI upgrade. Below is a list of what I am hoping to replace this time, the parts and a couple questions.


- New head gasket kit
- New Head bolts
- New Water pump & Gasket
- New Timing Chain and gears
- New Radiator hoses
- Rings? (I did a compression test and showed 155-160 on all the other cylinders. Should I even both doing the rings?)

I plan on pulling the heads and getting them looked at and machined. It’s not that expensive considering all of the work that needs to be done. Is there anything else that I need to be looking after while I’m this deep into the engine?

 

[MO Viet Vet]

Have the machine shop do pressure test of heads and do the valve guides and seals. You are going to need to take the ridge off the top of the cylinders and hone the cylinders. Clean, clean, clean. Do all the heater hoses and do a thermostat. Yes do the rings. New crank bearings and rod bearings.

 

[hotrdd]

Forgot to mention that I was not planning on pulling the engine to do this work. But I did already account for the machine shop to go through the heads. Can I do new crank and rod bearing without pulling the engine? I’ve never done them before and I have a transfer case underneath so I’m hoping I don’t need to pull that whole thing.

I looked at changing the cam and heads with some from Jegs but I’m not sure that’s worth the extra $2000 to get 60HP more.

I actually had a buddy at work today, with the same Yukon tell me that he blew his head gasket last night. Crazy!

 

[MO Viet Vet]

Every time I have done the rod and crank bearings the engine was out of a rig. I assume you could do it in the rig but would just need to remove more for access. That would be a hell of a job to do. If you have enough miles on the engine and like the rig and meets your needs and is paid off and you just want to keep it, then pull the engine and go thru it.

 

[hotrdd]

So "Knock on wood" thing are going better than expected. I have 2.5 hrs into it and I have the engine taken all the way down to the heads. Including flushing the engine out, removing the radiator fan, AC, intake and all the electrical connectors. I'm assuming I need to remove the power steering pump bracket that was holding the AC but for the life of me I can't get the lower right corner lose. Do I need to pull the pulley to get at a bolt because that pulley is stuck on. I tried to use an allen socket to loosen it but no luck. Even some WD40 over night didn't help.

 

[MO Viet Vet]

WD40 is a lubricant, not a penetrant.

 

[hotrdd]

Sorry it wasn’t actually WD40 it was one of the name brand liquid wrench penetrating sprays.

I assume that that center allen bolt comes off counter clockwise?

 

[MO Viet Vet]

Are you talking about the pulley on the front of the a/c compressor?

 

[hotrdd]

No I took the AC compressor off the big mounting bracket and am now at the pulley for the steering pump below the AC unit. I believe I need to remove that whole bracket in order to get the driver’s side head off. I have the bracket mostly loose but there is one bolt somewhere on the bottom outside corner that is holding it in place.

Engine tear down and flush 2.5 hrs
Power steering pulley removal = the same as engine tear down

 

[MO Viet Vet]

Details are always better than generalizations. The power steering pulley will likely take a special pulley puller to remove. So yes, remove it for bolt access. The center front of the pulley likely has a hat that has a step groove in it to allow for the puller to engage and then used to pull the pulley. Takes a special tool to do it. Likely can rent and be shown how to use at a parts store or a friend.

 

[hotrdd]

Well you were right. I new engine may have been the way to go. Turns out I have two cracked heads with cracks into the intake ports. But I'm going to go with some reman heads since I already have the rest of the engine upgrades ready for the new heads. The only other thing I could do is possible pull the engine to paint it.

 

[MO Viet Vet]

Let us all know how it all goes. Good luck.

 

[hotrdd]

Rocker Arms???

So it turns out the heads were both cracked so I’m putting a new set on and basically doing a full rebuild including new accessories where they will be hard to get at again later. Anyway I got to the point where I need to put the rocker arms on but when I follow the Haynes Manual it is all wrong. I follow the sequence which says to go to TDC and then torque specific intakes and exhaust bolts to 22 ft/lbs well that just leaves all of the valves stuck open and I can no longer turn the engine over. I tested the 22 ft/lbs with three torque wrenches and they all agree. There has to be a different system.

I found a different sequence on a website but it recommends just tightening them until the rockers are “just tight†and then another ½ turn.

Does anyone have the right instructions for a 1999 GMC Yukon 5.7L Vortec ???

 

[hotrdd]

Does anyone have the instruction for installing the rockers on this engine?

 

[mbumgua]

Did you replace the cam and lifters or are you gong back with old? It makes a difference as the old lifters should still have oil in them and new ones won't have any. New ones will only have a slight spring pressure. Old ones still have oil in if you didn't take them apart and clean them. Haynes manual should read 22 in-lbs rather than ft-lbs. Try that and see if it works better; and let us know.

 

[mbumgua]

Or you can do as I do and position the crank as indicated in the Haynes manual and adjust each valve in sequence as Haynes indicates. but instead of torquing with torque wrench spin each push rod between thumb and fore finger as you slowly tighten the rocker nut.You will feel the slight difference in effort when the push rod starts compressing the spring inside the lifter. At this point you tighten 1/4 to 1/2 turn more and move on to the next. Good Luck!

 

[lesterl]

Make shure you got the right push rods in the right intake/ exhaust are different length IIRC....

Also did you get aftermarket parts (rockers/ pushrods/ lifters), you may have an incompatibility.....

 

[hotrdd]

All of my push rods were the same length?



Truck is back up and running but I am now trying to get the valves perfect. The instructions I found indicated the sequence below to tighten the valves. However since the truck is running I was planning to back them off until they clatter, then tighten until the clatter stops and then go a ½ turn. But when I tried this the clatter wasn’t that easy to hear. Is there a trick to this? For some of the rockers I could feel the clatter but it was hard to tell when it stopped.

#1
Intake 1,2,5,7
Exhaust 1,3,4,8

#2
Intake 3,4,6,8
Exhaust 2,5,6,7

 

[lesterl]

Could be different on a 350, I know on the GM V6's I am always careful which I pull out where they came from they go back there.....

P.S. when I pull pushrods I use a big pair of pliars and pop the rocker arm open and pull the pushrod out, no need to adjust rockers... They do make a tool to do this, but I am kinda redneck of sorts.....