GWB: Dropped Seats Suck

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Great White Bus
1st Engine Drop

Dropped Seats Suck

At the end of the summer of 2005 I started noticing a serious loss of power, and valve adjustment checks showed the #1 cylinder had a sunk valve seat. Another Type 2 listmember had sent me a 1700 cyl head a while back so I tackled cleaning it up and making sure the valves sealed.

The Windex Test

First thing I should mention is the "Windex" test. What`s a Windex test? Flip the head combustion chamber up. Stick objects underneath to make the head level, and pour Windex into the combustion chambers. Don`t have Windex? Use water, gasoline, etc. Whatever. I just happened to have Windex handy when I initially tested this head.

What you`re looking for is any of the solution leaking past the valves. In my case, one of the intake valves was leaking a measurable amount out the intake port. If it leaked this much Windex at zero compression, imagine how much combustion is getting out at 7:1 compression!

Inspecting the 1700 Head

When I discovered my sunk valve seat, and checked my bank (nada), I decided to see what could be done to the head I was sent. It didn`t have sunk valve seats and the valve tips were all within a 1/4" of each other.

Cleaning Up

Off to PepBoys for some tools. I picked up a valve spring compressor, valve lapping compound, and lapping tools. Total around $20.

I pulled the springs and checked the rock of the valves in the guides first. Barely noticable. Sweet, no new guides needed. But when I pulled the valves out there was a HUGE amount of carbon buildup on all the valves, especially the intakes. I found the source of my leak.

I put a brass wire wheel on my drill press and cleaned the carbon off the valves and set them aside, matched with their springs and retainers, marked to replace them in the same cylinder. Then I went at the seats with a brass wheel on my Dremel. I went through 3 wheels before I was done. That carbon is TOUGH. But I got everything cleaned up.

Lapping The Valves

The lapping compound sold at Pep Boys consists of 2 parts: Coarse and Fine. Obviously you want to use the Coarse compound to cut any large bumps, and use Fine to finish and reduce the scratches.

I spent about 15 minutes per valve for each compound. The valve face and seat were beautifully smooth. Not polished, but absolutely smooth to the touch, and no scratches or gouges were visible. I then cleaned everything up with carb cleaner to make sure none of the grit from the compounds was left behind.

Reassembly

I soaked the springs and retainers in Parts Dip for a few minutes, wiped down, and then wiped with motor oil to resist rust. Reassembly was the same as assembly. Everything went together smoothly with no problems.

The head now passed the Windex test with flying colors. I even tried filling the combustion chambers with carb cleaner (a much thinner solution) and again no leaks found. The head was ready to rock!

Dropping The Engine

We had pulled Troy`s engine a couple weeks before and it was easy as pie. Not so on the GWB. And here`s why:

It`s barely noticable, but the skirt between the fan shroud and the bumper is actually pushed in about two inches. I know, two inches isn`t much. But in this case it was enough to keep the engine from coming out smoothly - The shroud was hanging on the skirt! By the time we figured out that we weren`t going to get the engine out with the shroud on, it was too late. We couldn`t get the engine back on the tranny either!

After much finangling and use of my new three foot pry bar (and destruction of that pretty blue finish on the fan shroud) we finally popped it loose.

Blocking Cooling Airflow

Once it was out, we found some interesting things:

From left to right:

• Spark plug and socket resting on the head over the #1 cylinder


• Handfulls of gunk blocking airflow
• More gunk

It`s a wonder the engine ran at all! This just shows the durability of the Type IV engine...

Pulling The Head

So off comes the head! Well, not quite... I pulled the valve train off the passenger side head, then undid the nuts in the reverse of the torque sequence. I wasn`t worried about the head warping, but didn`t want to unevenly stress the studs and, by extension, the case. I was planning on reusing the pistons and cylinders, using the new 1700 piston rings I bought to tighten things up.

The head did NOT want to come off. I thought this was odd considering the 1700 used copper head gasket rings, instead of lapping the cylinders to the heads. This should have been a warning flag...

After much beating with a rubber mallet, the head finally came off... With the cylinders attached! More beating to get the cylinders free. Then I found there were no gaskets. Strange, but a rebuild is to be expected at some point during 30-some years on the road.

Hmm... The combustion chambers on the head look larger than the ones on my 1700 head. I test fit one of the cylinders to my 1700 head, too big! I grab one of Troy`s 2.0 heads and test fit... Perfect. Ahhh... The engine was upgraded to a 2.0 at some point. It makes sense, since it doesn`t really cost much more to cut the case and head for 2.0 cylinders. It`s what I would have done if I was doing a complete rebuild.

But this left me in a conundrum. I couldn`t use my 1700 rings, and I couldn`t use my 1700 head. The rings weren`t a deal breaker, but the head was. I didn`t have a 2.0 head handy. But Troy did! He has 2 78`s and one engine is torn down for a rebuild. So I got to use one of his heads.

Reassembly

I lapped the cylinders to the loaner 2.0 head using the same lapping compounds I used for the valves. I spent about 20 minutes on each cylinder, and cleaned up with carb cleaner. I put the cylinders back on the pistons and studs (using Troy`s handy ring compressor) and then lined up the head.

Everything went back together nicely. Did the two stage torque on the head nuts and reinstalled the valve train. I then tackled cleaning up the mess on my engine. Grease, oil, dirt, gunk, etc, all needed to go away. I used lots of Purple Power and the garden hose. The engine practically shined after that.

Back Into the Bus

Putting the engine back into the bus, even without the fan shroud, was not easy. Apparently during the prying-banging-cursing session getting it out we bent one of the studs. I was determined to get things back in though, so after much finangling and sweet talking the engine finally slid home.

After hooking the intake and exhaust back up I hit the starter. It barely coughed and died. I was flipping out. Turns out I had forgotten to adjust the valves on the head I just put on. Oops. A quick valve adjustment later and the bus ran tight!

Test Drive

I let it warm up a bit then drove around the block. Aside from clouds of white smoke from the exhaust, it ran strong. Nothing really dramatic but smoother and more consistent power.

Obviously the mixture is off. Also, I forgot to hook up the booster line to the metal pipe in the engine compartment. So there was a great big vacuum leak. I hooked everything back up, but still getting smoke.

I decided to go ahead and head home and play with the carbs later. When I got to adjust them, they balanced easily, and I was able to make the smoke go away. Still not really dialed in, but solid.

We`ll have to see how things go over the winter...