FZJ 80 HG / Valve Job Details

[DTAYLOR]

This truck has 225k on it and the Hg just blew. I'm in the middle of replacing it, and want to replace all prudent and logical parts that may wear out or break in the next 250k or so. I am betting I can get 500k on this truck unless I wreck it.

I'm having the head shaved, valve job, leak test done at a machine shop.

So what is the group's thought on the amount of metal I can have shaved off the head? I have seen from .001 to .008. Anyone differ on this?

The carbon build up on the pistons obviously needs to be removed, and those little 1.5" scotchbright discs on the straight shaft air tool seem to do a nice job. Is there a better method known out there?

There are ports between the cylinders that sit at a 45 degree angle and are recessed into the block. I have no clue what these are. First, what are they? Second, don't they need cleaning? I would think so if it is practical.

The timing chain tensioners look about half way worn out. I have heard nothing about replaceing them. Anyone ever done this when you have the head off?

How about the timing chain itself?

Parts being replaced: All HG parts, hoses, water pump, stat, idler pulley, alt brush pack, heater hoses, PS pump gskts, dist cap, rotor, wires, plugs. Replaced fan clutch and belts in last 30k.

Also powder coating air filter can, ps pump res, various brakets, bolts, intake, and valve cover in bright Harley orange, just for the fun of it.

So, tell me what else I should replace, while Cdan is giving this stuff away?

Dan Taylor

 

[landtank]

The slippers require that you remove the front casing which requires removal of the oil pan. Not a bad idea if you are leaking a little oil back at the tranny and the pan arch seal is suspect.

 

[IdahoDoug]

Dan,

I took .010 off mine and it seems to have made a difference in performance. The ports are either coolant or oil. Can't remember but I think they're coolant in between each cylinder atop the block.

With the battery tray out and the truck down for a few days more, consider pulling the radiator and having it professionally cleaned unless you know it's in good nick (some Aussie talk for our friends down under..).

DougM

 

[RavenTai]

The carbon build up on the pistons obviously needs to be removed, and those little 1.5" scotchbright discs on the straight shaft air tool seem to do a nice job. Is there a better method known out there?

I would do this by hand,

usign a die grinder you could damage the finish on the bore if you bumped it, if you take any apreciable ammount of metal off the pistons you could affect ballance, top of the cylinger walls will also need to be de-carboned, by hand is best.

 

[landtank]

I'm concerned about having the head surfaced. Sure if it's flat, but what if it's not. When manufactured the head is machined so that it is the bearing surface for the cams are straight with the head's surface. Now even though the surface might not be flat it is still aligned to the cam bearings. Now you take that head and re-surface it flat there is no chance of those cam surfaces getting any closer to being back to where they were originally. At least if you were to torque down the head un-machined it would take some of that warp out wouldn't it, after all it's not as if it's cast iron.

 

[DTAYLOR]

pull the oil pan, huh?

Rick,

So maybe just an in frame overhaul as well? With 225k, plans to put on a blower, sounds like a good excuse to get dirtier, buy more parts and make both top and bottom stronger... I could probably get rings, bearings and an oil pump replaced in what, a day at most? Something to consider.

Doug,

The radiator core looks literally new from the cap view, and draining the anti freeze I put in it last summer reveals no foreign matter like corrosion, rust, or anything else. I may find something if I drain 100% of it though.

 

[RavenTai]

if you are going to pull the head timing cover and both pans just go ahead and pull the motor. you will be doing %98 of the work of removing it including having it out of its mounts and haninging on on a engine lift to do all of the above.

you will have much more fun with a rebuild wile on a stand.

 

[semlin]

i would add t-stat, fuel filter, fuel pump regulator, clean the rail and injectors, and replace the starter contacts. i would subtract idler pulley unless it's bad.

i replaced my tensioner but this was because the 93's have an older finicky design. when you say worn do you mean the tensioner or slipper? my old tensioner had no wear that i recall.

i ended up with ten thousandths off and a fair amount of that was needed to straighten it. I would have the valves tested before i ground them. Mine were perfect except the very middle ones which was probably due to the warp.

 

[ElJefe]

I'm concerned about having the head surfaced. Sure if it's flat, but what if it's not. When manufactured the head is machined so that it is the bearing surface for the cams are straight with the head's surface. Now even though the surface might not be flat it is still aligned to the cam bearings. Now you take that head and re-surface it flat there is no chance of those cam surfaces getting any closer to being back to where they were originally. At least if you were to torque down the head un-machined it would take some of that warp out wouldn't it, after all it's not as if it's cast iron.

This is a very good point. Are all of the people that are doing their HG having the shops check the cam allignment?? The old BMW straight 6 had a cast iron block and alluminum head, and the most expensive part of doing a HG on those cars was having the cam girdles allign bored and honed for oversize cam bearings. The spec for runout on the cam bearings was something like .0015 max. On those motors the cams ran in bearings that you could get in several oversizes just for having to rebore the cam girdles. On these engines the cams run right in the aluminum IIRC.

Possibly this is why Toyota officially requires replacement of the head rather than ANY milling. On those BMW engines, if you did not rebore the cams for allignment after milling, you might as well put another HG replacement on your calendar.

 

[bjowett]

If you are having the valves and seats cut, you may need shims to get everything back in spec. About 75% of mine were too tight after they were done. $8!!! a pop adds up quick... measure carefully and let me know what you need, I have a about 30 of various thicknesses.

 

[DTAYLOR]

Sem.

Good question. I really don't know the difference. The wear I see is on two verticle almost banana shped black peices on either side of the t chain. I could see them being referred to as either slippers or tensioners. The chain slides on them as it goes around AND they keep tension on it. You tell me what they are.

D

 

[semlin]

those are the chain slippers. the tensioner is the spring loaded cylinder bolted into the side of head next to the water pipe.

to replace the chain slippers I think you have to pull the timing chain cover but you had better do it if they are worn. this means dropping the oil pans in which case you might want to think over raventai's suggestion and just pull the block. my local machine shop said the labour on doing the block would only be about $450.

 

[DTAYLOR]

slippers...

Definatly are worn, at least half way. What would they do for $450? Sounds like labor to put in bearings, rings, and either turn the crank, or bore the block. There can't be that much labor to just do a bench to or motor stand job. Machine shops around here only work on what you take them, they don't do R&R work.

 

[Slomo]

I am certainly no expert so correct me if I am wrong. I have my head off right now as well and was inspecting the chain slippers today. It looks to me like they were molded with raised edges on them to help keep the chain from sliding fore and aft.

 

[DTAYLOR]

ex = has been; spert = drop of water in a hurry...

Slomo,

I'm no expert either, but I did stay at a ..... nevermind.

I had a long discussion with Cdan thursday about this very issue. After which I took a close look, and came to the same conclusion you did. I would now say they look "normal" to me.

I can also see that Mr. T was smart enough to make a part that will last basically forever since he requires the oil pan to be pulled off in order to access it (the slipper and guide) and the also very durable timing chain.

Further, we also have in evidence numerous Hg jobs at low to very high milage on this site with no mention of replacing slipper, guide, and timing chain parts.

Cdan also issued a hearty "git r dun" without messing with the bottom half once we discussed the overall outlook of the rest of the motor parts, and performance prior to HG failure.

My ponderance at this point in the process mainly rides with how I want to use the truck from this point forward. I want to get another 250k to 275k miles out of it (about three years worth) then give it to one of my sons to do with as they see fit.

Depending on which one gets it, you will either see it made into a low rider with remote switches to make it bounce, or see it made into a beach club cruiser who's primary duty is looking cool at the volleyball court. Oh, the humanity! I digress...

I would love to have a blower on it, thanks to Jim Reiss, who let me drive his lifted 80 with one. AWSOME smooth power! The old bottom end likely will not hold under those driving conditions, so to OH the bottom end now just seems to make sense. We will see..

(BTW Cdan called the ps a "slipper" and the ds a "guide". I take it as a lesson).

 

[Slomo]

Thanks for the info update. I definitely feel better about mine now. CDan is the man.