This week has been a very stressful week for me as my pride and joy has had to go and get some serious repairs. During this Covid lockdown like many of us we are finding things to do and pamper our cars. I have been no exception to that of course, with a LED upgrades going on, carb spacer swap out all of which I have to post about and will be coming soon. But this update jumps the queue. I said when I was restoring my car I would post about the good, bad and everything else. This is one of those gone wrong posts. Mustang Maniac may cover my story this weekend as well, to help each other out we have swapped some photos between us. 👍

Background is that I had a mini project to replace a carburetor spacer from the old metal 1″ style to the new phenolic spacer. This meant that I ‘had’ to test drive the car t make sure all was OK, while on my way to take some exercise of course. During the shortish journey of ten miles round trip or so the car started to make a whine noise, almost like a super charger. This annoying noise was coming from the gearbox area. The car started to make a significant thud when selecting reverse or drive gears from park or neutral. I called Adam at Mustang Maniac to explain what was going on. He listened to my explanation and said that he would open a slot for me at their yard.

I drove down on the Monday morning very gently I might add and the whine was getting worse. I knew something was wrong and hoped it was an adjustment somewhere. When I arrived and was greeted by Adam and Yogi, both said to put it straight onto ramps when they heard it. Within a couple of minutes Yogi had listened, diagnosed the problem and said gearbox was trashing itself, and probably the torque converter too. This was bad, real bad. The decision was made to drop the gearbox out to investigate after the dipstick for the gearbox was checked and was covered in foam.

The oil was drained out and the proper dark red colour was a foaming mess of pink slop.

While the “liquid gold” as Adam calls it, was draining out the prop was removed, the speedo cable, handbrake cables, and the exhaust split from the headers.

A conversation was had with Adam and I was given the option of what gearbox I would like and he went of to get it from his secret stock. The sound of expensive parts arriving in the trolley was sad sound to hear. Adam returning with the parts.

Yogi and Stuart jacked up the gearbox lift up to the gearbox to support the weight while it was lowered out.

These C4 gearboxes were clever for their time in the fact that they had cooling pipes that ran from the gearbox, up to the front of the car, which were then in turn connected to the bottom of the radiator. The pipes in the bottom section of the radiator shares the cooling with the engine block’s coolant. The cooled oil returns back to the gearbox ready to reapeat the process. The cooling pipes have their own entry and exit fittings to the radiator. It was here that the problem was caused; the internal loop of pipe within the radiator had failed somewhere. The water pressure from the radiator had forced water into the oil cooler channels because the gearbox oil is under less pressure than the engine’s coolant.

With the gearbox down on the floor the investigation could begin. Yogi had an airline on the cooling pipes which were still on the car, with a jet of air the water was expelled at a high pressure, confirmed water (and anti-freeze) was in the gearbox.

The bottom of the C4 gearbox has a removable pan that allows access to a serviceable filter to protect the delicate interior. The filter had done its job and stopped all sorts of debris and was getting near to clogged. The gearbox tension bands, seals metal on metal parts had indeed started to disintegrate. By feeling the gunge on the filter there was some swarf or tiny metal particles. Yogi was right, the gearbox was starting to eat itself, and it was very hungry.

The torque converter was removed and checked, draining the contents more swarf was found inside. With the oil pan emptied more traces of fine swarf were found at the bottom. The expense was starting to ramp up.

The water had in effect contaminated the oil and strated to break the oil’s properties down and failed to lubricate the gearbox along with the torque converter, thus unable to keep it all cool. The end result was the bands were slipping in the gearbox and the engine coolant had caused the gearbox to overheat. I was told I was a lucky boy as it could of just let go, dumping the contents of the gearbox on the side of the road leaving me stranded. The radiator was low and topping it up gave us an idea of how much water had got unto the gearbox. The top up was almost one liter.

The new gearbox was a genuine 1966 date coded C4 green dot fully rebuilt gearbox. This was a rare part, let alone to have a choice of them straight out of stock.

The new torque converter was screwed into the bell housing and the careful alignment to refit back into place. The gearbox was lifted up into place and little magic the gearbox was roughly in place.

With the gearbox now bolted into place, the finely tuned machine that is Mustang Maniac had a gearbox out and back in place within a day. Yogi was pleased with the day’s work, it was time for me to go home and leave my very poorly car on ramps for the night.

The next day I was back at the yard in the afternoon. Yogi had completed the rest of the refit and and all was back in place.

The next problem was the radiator the proximate cause of the problem. Again Adam asked me what style, cooling performance and look that I wanted. I went for the upgraded three row (which I already had) from the standard factory two row, with the OEM stock look. The expenses were ramping up even more.

Yogi pressure tested the old radiator and it had indeed failed in the oil cooler loop. A rare failure by all accounts that had catastrophic consequences on the gearbox. Why it failed we can’t be sure, perhaps a failed weld, or rusted out or crack? Without cutting the radiator open we won’t know.

The engine block had to be drained and flushed before the new radiator could be fitted and more fluids replaced.

The rest of the plumbing was reconnected and filled up. The car fired up and the gearbox whine was gone. Selecting a gear; there was no thud and the engine didn’t stall out.

The engine idle on the carb had to be reset and a road test. The was a little more dark art of carburettor fettling going on after the road test, the tuned ear of Yogi jumping from one screw adjustment to another and back again.

My drive home was a different car altogether, it was again effortless and a joy to drive. The joy of owning a classic car can be bitter sweet. I have had some wonderful sweet treats, and then this week the very bitter pill of a transmission failure. There you have it, a very big downer for me with things not going to plan. I was lucky that I got to Mustang Maniac how and when I did. Keeping it quiet is not what it’s about for me, this blog shows the good with the bad.

A huge “Thank You” to all at Mustang Maniac.

I have some mini projects coming up and detailing product reviews too, I will be posting them soon. But, first I have an excuse to clean the car engine bay again as it got a bit grubby after all the work being done on it. Many wouldn’t notice anything to be honest, as it was cleaned up pretty well. But I’m just pleased my little lady is back home and I again can pamper her and give her a nice clean up. I’m lucky to own a classic Mustang so I can’t complain. I don’t thrash my car so perhaps that helped me in getting down to the yard without a breakdown. If you own a classic car these things can happen, but not to often I hope!