93 HG essentially done - observations

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Aug 8, 2003
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Got Bessie all together except a few heater hoses and the battery box. I noted that I had cut a scratch in one of the water valve metal heater hoses years ago when I put all new hoses on, so I'm using a trick that I may have learned here. You sand it down, then spray paint on it and sand it again and essentially fill the scratch with paint. Won't work on a deep cut, though.

Anyhow, there was no sign of head gasket distress except that it peeled off the block near #6 notably easier than the rest of the block. Compared to the 97, this gasket looked quite good and was adhered down much better. The plastic sealing skin came off easily with the gasket on the 97 but was well attached and largely remained on the block with the 93. Also, there was much less cylinder sealing ring denting into the block, and the places where the 97's gasket were swollen and disintegrating into the cooling jacket were solid - looked great. For whatever reason, it appeared the gasket on the 97 moved around a lot more during its life - making wear lines and such on the block and head. Overall, with mileage very close (156k - 93/131k - 97) the 93 gasket was in far better shape. Even feels stiffer when you're holding it in your hands vs the 97's "I'm so beat up, coolant soaked, delaminated" floppy feeling. I'll post photos now that my wife and camera are home.

The block sealing surface was in much better shape and required half the time to clean up. The junk on the piston tops was also much easier to clean off for some reason - almost wiped off. But #6 literally DID simply wipe off all the way to a bare metal surface from the leak starting the steam cleaning process. No question I had a leak and I am very pleased it was me driving it when it happened.

Random comments:

-The heater valve has a valve design that doesn't allow you to stop all flow to the rear heater. Only about half of it is stopped, which probably avoids stagnation. I could see no way to easily modify it to shut off all the way which is why I was looking at it - my trucks both seem to 'heat' fresh air slightly in the summer and it irritates me.
-This engine and its systems are really well engineered. Everything is designed to last forever and be serviced. The alternator bracket is cast iron and weighs about 3 lbs, the throttle body is a work of art and simplicity, the head is massively constructed and the exhaust manifolds are unbelievably high end metal and fit. Not a single fastener was rusted in place or broke, and other than my intake manifold-in-place trick there's plenty of room to swing wrenches and see what you're doing. The only source of irritation in the three times I've done this is the EGR valve.
-Got the fuel injectors pretested, cleaned, then post tested. No huge discrepancies, but they're all flowing exactly the same now and an overall higher flow. Cost me $15 each and got paper graphs, etc. He even checked the internal screen filters - all OK.
-Because this is my baby, EVERY fastener went together with antisieze, EVERY connector went together with dielectric grease, and EVERY ground got a light sanding.
-I put new alternator brushes on the 97 ($15? from Dan) and they were 2/3 used up at 131k. On the 93 they were more like 3/4 used up at 156k and I suspect this is because since new we've run it with the lights on - 100%.
-On the 97, there is a black metal strut from the intake manifold's left most point (between runners #3/#4) down to the block. My 93 does not have this. Do any of you have one on a 93/94?? It's easily seen standing at the LF tire.


Can't wait to start it up Sunday.

DougM
 
interesting info. thanks doug. i'm at 151k and watching things very closely.
 
So Doug, after all that do you think your maintenance routines are helping or not??? Come on man, give me a reason to rationalize my mania!!! :flipoff2:
 
I have no measurable data to say they are. In fact, on the 93 the valve shims the cams run on were scuffed a bit. I wonder if the carbon loosened in cyl 6 was getting past the rings into the oil and then to the cams to do that as I limped home? Not likely - I think it would have to get through the Toyota filter (the good one). On the 97 they were mirrors - not the faintest trace. That's appearance. Function wise, the tighter tolerances of the valve train could be clearly felt on the 93 so that's good. I think the bottom end bearings also felt tighter - both as measured by resistance to spinning the engine by hand. Wonder how much HP that tightness costs me??

One thing that can be said is that I've really been rough on the 93's engine with all those full throttle towing events I brag about. Yet no signs of stress or discoloration in the cylinder environment or the valvetrain. That's nice to see and hopefully a result of top notch consumables and early changeouts.

I'd expect the internal wear to be very low, and my original radiator shows very little deposits in the cooling slits - practically negligable.

DougM
 
IdahoDoug said:
-The heater valve has a valve design that doesn't allow you to stop all flow to the rear heater. Only about half of it is stopped, which probably avoids stagnation. I could see no way to easily modify it to shut off all the way which is why I was looking at it - my trucks both seem to 'heat' fresh air slightly in the summer and it irritates me.


that is interesting, I get warm air in the summer also, figured it was firewall heat but that is interesting. need to do something about that.
 
Doug that bracket you mentioned is used on 95-97 only.
 
Raven,

Yeah, I've removed the heater valve some 4 times over the years and noted how it is indexed very simply by where the cable housing is held in clamp. I was thinking of making a mark for summer (would cause the valve to be fully closed) and a mark for winter (valve would be fully opened on hot). but alas it won't work. We'll have to devise a second in line valve that's a simple shut off valve. Would suggest it have a provision for SOME flow to trickle through, however.

It's a pretty high end looking valve, too.

So, Dan - what's the rattle on one of those brackets? I actually like what it does, which is supporting the fairly weighty intake manifold and might include one on my next order if it's not so bad. Nice retrofit for Bessie...

DougM
 
Yes, the holes are there,
 
interesting about this non-closing heater valve. I had just assumed that was because the outside air was naturally heated somewhere in the engine bay or in the ducts...
But no biggie.
 
IdahoDoug said:
Random comments:

-The heater valve has a valve design that doesn't allow you to stop all flow to the rear heater. Only about half of it is stopped, which probably avoids stagnation. I could see no way to easily modify it to shut off all the way which is why I was looking at it - my trucks both seem to 'heat' fresh air slightly in the summer and it irritates me.

My valve allows me to control flow to both front and rear heaters.

I removed the heater valve and tested it with a garden hose. The valve did look like it was half stopped when closed, but when tested with garden hose, it was 100% stopped , no water came out from the other end. However, it is very a sensitive valve, water will go through the valve even when the valve is slightly opened. I installed the valve by making sure that it was 100% closed, needed to work on the cable a little bit. It is all good and no more warm air.

Edit after reading RT's Q: I did this on a '93 LC
 
Last edited:
good info.

could a small return sping help wuith closing it? not sure the actuator can handle the extra load though.

Is the LC valve full manual to the contol pannel or doe it have an electrical actuator also?

summer will be here shortly, I will be doing soemthing this year if not just taking the cable off and wiring it shut.
 
ok did some digging in the manual and it is actually pretty vague here but from a crappy drawing it looks like the heater valve might be connected by a cable to the "AIR MIX SERVOMOTOR"

The air mix servomotor opens or closes a door to allow air to flow through or bypass the heater core, so the more air flows through the heater core the more the water valve opens.

If it is truly a servo motor then it probably would burn it up to put a spring load on it.

There is a procedure to rig the water valve.

ADJUSTMENT
ADJUST WATER VALVE CONTROL CABLE
(a) Set the vehicle in these conditions.
Ignition switch on.
Blower speed control switch on.
Temperature control switch to ”COOL” position.
(b) Set the water valve to ”COOL” position, install the control
cable and lock the clamp.
 
Medtro,

Interesting and nice detective work. On mine, when I looked in the open pipe at the actual valve, it moved freely but came to a stop before fully closing - leaving a small crescent shaped gap. Is that how yours looked? This was from the driver's side looking into it.

If that's the case - the valve can shut off all water - then I'm going to 'index' mine to be shut completely in the cool position. It's easy enough to do as you simply use a screwdriver to release the spring loaded clamp that holds the cable housing. Then slide the housing so the valve's all the way shut and resecure the spring clamp. Just be very careful not to drop that clamp as it's above the NoMan's Land at the firewall behind the engine.

DougM
 
just make sure you are not preloading the cable, not sure what will happen if the travel of the servomotr is limited.


I am going to try same.
 
Good point on the preloading. However, with the radio on AM and the right frequency, I can hear the static from my servomotor running when I adjust temp and will use this to know the motor is not sitting straining against a premature stop.

DougM
 
IdahoDoug said:
Interesting and nice detective work. On mine, when I looked in the open pipe at the actual valve, it moved freely but came to a stop before fully closing - leaving a small crescent shaped gap. Is that how yours looked? This was from the driver's side looking into it.

Yes

IdahoDoug said:
If that's the case - the valve can shut off all water - then I'm going to 'index' mine to be shut completely in the cool position. It's easy enough to do as you simply use a screwdriver to release the spring loaded clamp that holds the cable housing. Then slide the housing so the valve's all the way shut and resecure the spring clamp. Just be very careful not to drop that clamp as it's above the NoMan's Land at the firewall behind the engine.

DougM

May be you do have a different valve. My clamp is part of the valve/bracket system, it will not fall out.
 
IdahoDoug said:
Good point on the preloading. However, with the radio on AM and the right frequency, I can hear the static from my servomotor running when I adjust temp and will use this to know the motor is not sitting straining against a premature stop.

DougM

This is getting into more technical now :bounce2: :bounce:

What is that frequency?
 
RavenTai said:
ok did some digging in the manual and it is actually pretty vague here but from a crappy drawing it looks like the heater valve might be connected by a cable to the "AIR MIX SERVOMOTOR"

The air mix servomotor opens or closes a door to allow air to flow through or bypass the heater core, so the more air flows through the heater core the more the water valve opens.

If it is truly a servo motor then it probably would burn it up to put a spring load on it.

There is a procedure to rig the water valve.


this should be posted into one of the faq'd h/g threads. my plan was just to reconnect at same position i connected. very good info.
 

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