1979 Chevrolet C70 Conversion to OEM Air Conditioning

[Airdirect]

Here are the measurements for my bow tie decal.

[Pvmt-Pndr]

I apologize for the delay. The one I have will not work.

[Airdirect]

I could not find the larger bowtie sticker anywhere. All that were available were the size for pickups. My daughter (-in-law) Kaylyn did a beautiful job of creating one for me. I can't wait to get it installed. I will post another picture once it is on the grill.

[Airdirect]

Time for a update. We have driven this truck almost 40,000 miles. The drive train has been flawless except for the Air Conditioning. I am on my 4th A/C compressor. First Compressor locked up forcing me to flush the system and replace the dryer and evaporator. The second one developed a bad Freon leak, the third had the clutch start slipping. The A/C works great, just wished GM had used a different compressor in this era.

I hauled a tractor and other equipment up to a show in Southwest Missouri. I noticed that the engine started to miss and smoke at idle. Once off idle it was clean and smooth running like normal. I decided the rack and valves needed to be adjusted. When I got home, I removed the valve cover and adjusted the valve clearance. Overall everything was real close. The rack was perfect and needed no adjustment. Once this was completed I still had the miss and smoke.

I did another 2,700 mile trip to Northern Indiana. The engine ran find above idle and did not use or leak oil. We continued to have the miss and smoke only at idle. I am thinking I have a broken piston top, or failed Top compression ring. When I get some time and room in the shop I will remove the head to see what the problem is.

[jumpsoffrock]

That sucks to hear and I hope it ends up being something minor and easy. Love this project of yours.

[C10 - C90 Bill]

If your Detroit did not leak oil, there is something wrong with it !! Lol.

Hopefully it is something minor as mentioned.

Keep those old Detroit's going.

[Airdirect]

In my experience, the 53 series are much less prone to leak oil. The only oil leak I see is a few drops from the blower drain. This only happens when it sits overnight. I have left it idle overnight during cold weather and do not have any drips under it.

[C10 - C90 Bill]

Originally Posted by Airdirect

In my experience, the 53 series are much less prone to leak oil. The only oil leak I see is a few drops from the blower drain. This only happens when it sits overnight. I have left it idle overnight during cold weather and do not have any drips under it.

I'm not sure if the 4-53 or the 4-53T would be different, and I hate to say this, but I learned years ago not to let a 53 Series idle for a long period of time. I know of an oil company that would start their 6-53's early in the morning and they ended up having to rebuild what I believe was the top end on all their trucks. I don't even like my 2-53 to idle long at all, once it has hit operating temperature. I believe it has to do with the effects of low Oil Pressure. How does your Oil Pressure look at a long idle?

[Airdirect]

My oil pressure when hot at a stop light will drop to 5 psi. However during a long idle it will come back to 10 to 12 psi. My uncle was a supervisor in a DD overhaul facility, and he told me that 1.5 psi per 100 RPM was all that was necessary. I have spent the night many times on the road (bench seat) and in cold weather I let it idle all night. However I now have either a broken top ring or a head gasket problem, I have not opened it up yet to see. Will post what I find. I am leaning toward a head gasket. I stopped to have the oil and fuel filters changed at a major truck facility. After installing both primary and secondary fuel filters they could not get it to start. They ran it on ether (two tall cans worth) trying to get it to bleed. I sat in the customer lounge listening to it hammer on ether (they do not let customers into the shop) and was about to die. I got the mechanic's attention and was able to advise him that is was very easy to bleed, he must have a air leak on one or both of the fuel filters. Sure enough the primary filter can was not seated in the groove. Once it was seated the truck started. I have been wondering if that event could have started a head gasket failure.

[Airdirect]

I removed the cylinder head today. It appears that cylinder 2 has started pumping oil, most likely I will replace all pistons and liners, not sure what kits I will go back with. Here are pictures of what I found.

[jumpsoffrock]

That is great news, however it still looks like a lot of work. lol
That head must weight 20-30 lbs!(yes I'm kidding)

[Airdirect]

Yes, it is very heavy. I have ordered new pistons, sleeves, connecting rods, and injectors. I am upgrading to the newer style Silver 53 cross head pistons. This will allow me to run 5C60 injectors which will yeild a 5% increase in Horsepower and Torque.

[jumpsoffrock]

Are parts readily available or do you really have to hunt?

[Airdirect]

Parts are available from several different suppliers including the OEM. Piston and liner kits are fairly reasonable $350.00 range per hole.

[Airdirect]

I have installed new X head pistons and sleeves, in the picture I am measuring the difference in height between the sleeve flange and block deck. Manual says .046 to .050 with max difference between adjacent cylinders of .015. Three of mine measured .045 and one .044. I did clamp them down (not shown). Ready for head install.

[Airdirect]

Got the engine finished up, picture is just before the oil pan installation. Headed to our first tractor show of the year, Pawnee OK, about 8 hours (round trip). Should be a good break in run for the 4-53T.

[jumpsoffrock]

Man you really know how to get stuff done.

[Airdirect]

Made the round trip to Pawnee OK with no issues. Truck pulled good on the hills. Here is a picture of the tractor powering the Baker fan. The fan was used as a diagnostic tool back in the day. It would put a load on the Steam Tractor or in this case Diesel Tractor and allow you to observe and adjust engine settings for proper performance.

https://www.youtube.com/watch?v=YGYmNnkPHEg

[C10 - C90 Bill]

Good work and pretty quick to boot.

Like the farm tractor too.