Removing heads

[SteveMc]

I have two low compression cylinders on my 97 block and plan to remove the heads after christmas. Will be doing this with the engine in the vehicle. 87 Suburban. Being a 62 year old youngster, I plan to use a hydraulic crane to lift and set them to save the back.

Has anyone a suggeston how to hook them up to a chain or cable to do this?

Thanks in advance..

[rjschoolcraft]

You can attach to the bolt holes in each end.

However, I would highly recommend removing the engine to do this job. Working space is very limited, especially on the passenger side. Also, it is highly likely that you will find some other problem that will require removal once the heads are off.

Good luck!

[AndyL]

It took me 5 hours to do the passenger side head on my 86 Burb. That included a fair about of time cleaning.

That was with a buddy, both very experienced wrenchers. And not to forget, about 12 beers! :D

[DmaxMaverick]

I, too, prefer to remove the block if I can. The pan can always use sealing, as well as checking bearing clearances with a plastigage, and replacing the rear seal, oil pump, etc. It's sure nice to rotate the block over to get good look at everything.

If it's not practical, by all means, pull just the heads. I've done it many times, successfully. It's a tight fit, but very do-able. The accessory bracket bolts/holes at the ends of the block are fine for pulling. Just use a strap or chain attached to the bolts. They are relatively heavy, so be sure to use a suitable chain or strap. If you have access to specialty tools, there are head pulling loops that attach to the holes, and make it handy to have the center of gravity preset. It makes the installation very nice, as the head will be balanced and angled close to where you'll need it.

[NH2112]

When I did mine a few months ago on the 85 I pulled the radiator, water pump, and whole front of the engine off to do the timing set as well. This left plenty of room to stand and didn't require me to lift the heads at arm's length. You can also remove the inner fenders to get more room. I do agree that removing the engine is a good idea and it doesn't really add much time to the job.

[john8662]

SteveMc,

which cylinders are low on compression?

If they're beside one another, then I think that you're chasing a head gasket failure. But head gasket failure is about the only reason worth pulling the heads with the engine still in the chassis.

How low are your numbers?

[SteveMc]

Great information!

I put this engine in last March as a replacement to the origional that broke a crank. Upon examination I realized I had a low milage 97 instead on a 87 block. It came out of a 87 truck. The bearings and pump were tight and hash marks were still on the walls of the cylindars, so I suspected it was a engine replacement for the truck. Changed all the seals but did not remove the heads. Wrong!!!

After a thousand miles I checked the compresson and found #4 and # 8 low. Perty sure now it was a short block change and they used the old heads.
I should have checked before putting it back in> Never to old to learn.

Anyway thanks for the good info.

SteveMc

[john8662]

Whats the casting number off the heads? That will shed some light onto whether they installed the 6.5 block as a shortblock and then installed the 6.2 heads on it.

[SteveMc]

Casting numbers are 10137567. The listing I had showed they could be on any year from 82 thru 97.
My block was dated C037.

Will look things over closly in the am and decide if I want to try this without pulling the engine. Am leaning towards taking the engine out.

SteveMc

[SteveMc]

well the heads are off. Went ahead and pulled the engine. Figured it was much eaiser to stand beside the engine to work rather than kneeling on the radiator and bending over the engine.

Took me eleven hours. Only needed help getting the hood off. Head did not show any cracks however, the machine shop will clean them up better than I can. The hash marks in the cylinders go all the way to the top, so I believe the engine is low on miles.

Thanks for all the suggestion.

SteveMc

[john8662]

Good work!

The head casting number you have is for 6.5L heads, not 6.2 heads.

Have the machine shop take all the valves out of the heads, if you suspect bad heads (but only for cylinders in question). This will let them know what the seat surface in the heads look like (crack wise) and whether the valve mating surface is good.

Since you have the heads off, take some brake parts cleaner on a rag and wipe down the cylinder bores and the tops of the pistons, to clean off the black stuff.

Once cleaned, look closely for any cracks with the pistons on the two cylinders in question, and take note of any ridge ring found near the top of the cylinder bore. If you've got a ridge, it isn't going to be that low mileage, or it's been hot etc.

How did the head gaskets look? Did you see any places on the gaskets (mainly the two cyl's with low psi) where the metal ring in the gasket had separated from the gasket, sometimes they bulge into the cylinder/firing area.

[SteveMc]

Cleaned things up and took a look. Can not feel any top ridge ring. Top of one of the low cylinders was nice and smooth, as were two pistons on the other bank, with no sign of cracks. The other low cylinder piston along with the rest of the pistons have what looks like heat erosion especially across from the valve recesses. None are deeper than .005. Could bad injectors cause this? They were replaced when I got the engine. I have not had the heads off one of these engines before but, have never seen this much erosion in any engine I have messed with . Does anyone know an allowance for this?

Should I pull these pistons do you think?

SteveMc

[rjschoolcraft]

Try to post some photos. If you cannot get that to work, send them to me at ron@schoolcraftpowertrain.com so that I can see what you are talking about. Any minus material would be cause for concern.

[rjschoolcraft]

Steve,

I have not seen anything like this before. It almost looks like something has been on top of the piston. Jim (More Power) has uploaded the images for you. Here they are:

http://www.thedieselpage.com/images/schoolcraftforum01.jpg

http://www.thedieselpage.com/images/schoolcraftforum02.jpg

Maybe someone else will chime in.

If not, my recommendation is to be safe and pull them.

[AndyL]

Glow plug ends?

Look like impact marks from the pict. Maybe they broke off, got busted up by the piston and expelled though the exhaust. Then to be replaced by a previous owner?

[Slim shady]

The marks are to large to have had something very solid go thru the motor (my opinion only) I took my 145,000 mile 6.5 apart and had marks like those pictured although not as bad. I never had any problems with the motor and given what the pistons looked like would have swore something had been thru the motor.

The only warranty problem was a IP replacement at 65,000 miles. I wonder if they are heat related, did the hard coat anodizing deteriorate and they are heat related etching/wear.

Ronnie Joe could you look at the crank sensor post by Hank148. I would like to get an opinion on this topic, if you would.

[SteveMc]

Thanks for the thoughts. First time I've had a photo of mine on the web, Wow!! Looking at the pistons on scene, it reminds me of hitting metal with a cutting tourch. As though the metal was melted. I thought perhaps bad injectors. Five piston tops are just like this. The other three show now signs of damage. Have not heard anything from the machine shop on the heads. Hope they past the test.

Anyway, I will be checking with NAPA tomorrow for eight new pistons. Cylinder walls show no detectable wear. The origional cross hatch is present as far as I can see with the pistons still in. Cleaned the top ring area and no ridge can be felt with my finger. Will plastigage the mains and rods and replace same while I am in the area. Also new oil pump.

If anyone can think of anything else while Im at the this point, please let me know. I just want a reliable power plant that will pull my old Airstream(5000#) once and a while.

SteveMc

[rjschoolcraft]

The more I think about this, the more I think that AndyL hit the nail on the head. Glow plug tips passing through would likely make these kinds of marks. Was there any indication on the head?

[AndyL]

Originally posted by SteveMc:
If anyone can think of anything else while Im at the this point, please let me know. I just want a reliable power plant that will pull my old Airstream(5000#) once and a while.

SteveMc Steve, I worry you might have a little trouble with a 7000lb Burb + a 5000lb trailer and 3.43 gears.

Flat land will be manageable, any grade and your in trouble.

What size tires are you running?

[Turbo Al]

I kinda wonder if someone has run gas in this engine.

[john8662]

Definitly ate something, I'd know!

I suspect glow plug tips as well.

Now, I can't tell from the pictures, but the erosion looks to be on the bottom side of the piston on both sides of the Ricardo cup (mickey mouse ears).

Pull the piston and have a closer look.

When finding pistons, you'll most likely have the BEST luck getting the correct sized pistons from the Dealer. Here is why, GM used select fit pistons in these engines, so range of sizes is described. You will find what the correct size piston for the preticular bore will be from the bottom of the engine. On the pan rail of the engine, you will find a stamping directly below the cylinder in question. You will see a "C" or "D", etc. That is the size piston, they will vary, it will be very common to see half and half. I don't know what the pistons measure though, whether they vary a full .001" or between .0001" - .0009".

If you buy pistons in the aftermarket you'll have a tough time finding a piston that truely fits the bore. I've even noticed this on OS pistons. So a STD piston may be a little larger (most likely) than an OEM. Only way to know for sure will be to measure your bore with a mic and then measure the replacement piston and compare the two sizes to make sure that you have the appropriate cylinder clearance, which will be around .004"

Good thing you don't have a ridge ring, FYI, check the tops of the bore's for the ring, you may have NO ring at the bottom of the bore, but a very slight ring at the top. You want no ring at all, but with the miles, I suspect you don't have any ridge ring at all. Which is good, because you will surely get away with just a replacement piston.

If you're seeing erosion, the common causes for this is OIL in the combustion (too much) or an injector that stuck open under load.

[SteveMc]

Block and heads are in the machine shop. Heads showed a crack between the valves on one side and all the cups need replacing. Valves are not out yet so don't know about that. The routine valve guide fix should take care of the crack. The block won't be inspected untill next week. Will wait for that verdict with abated breath.

The origional owner set the rig up to tow a 30 foot Airstream. Origional engine had a Banks turbo put in at the dealership back in 87. I used IT to tow my 25 footer A/S all over the Southwest a couple years ago and it did ok. Had to stay out of overdrive, but running 55-60 it was fine. Got 11 mpg as an average. When the engine gave up(webs let go) I found this 97 and stayed away for the turbo to make it eaiser to work on.

Thanks to all

SteveMC

[john8662]

Heads..

I suspect the crack between the valves is going to be cosmetic. There is a fix to prevent coolant leakage in that area by installing a sleeve in the coolant passage. Instructions for that can be found in the members area.

The cracks seen on the precombustion chambers are also going to be normal, if you follow the guidelines. The cracks for precombustion chambers cannot exceed or reach the sealing line on the head where the gasket seals. So, a short crack that's about 1/4" long is going to be normal, and probably never a problem.

As for cracks on the bottom end, sure hold your breath, you've got a '97 506 cast block, that has the "wonderfull" piston oil spray coolers. So checking for cracks at the cooler nozzles and on the outside bolt holes on the main webs will be necessary. If everything is good, go ahead and install a Stud Girdle Kit, you're already there!