Oil Leaks on the White GTE

August 8, 2020


After our test drive of Tom Wilson’s Ferrari 250GTE last week, I noticed an increasing spot of oil gathering under the car. I hate to sound like a bad mechanic when they state the phrase “they all do that,” but almost all Ferraris leak oil! Unfortunately, some worse than others, and there is an amount of leakage that becomes excessive. Tom’s car has a belly pan, so with it installed the oil leak was masked until the oil soaked the pan, and found its way to the ground.

When I was working on the car these past several weeks, I noticed the oil leaks were coming from from several spots around the transmission, but with more driving, these leaks were getting worse. I carefully wiped each surface off and watched where the oil was coming from. This particular transmission has two separate oil reservoirs filled with two different types of oil. The rear section where the English Laycock overdrive uses 30 weight non-detergent motor oil, while the forward section is the Ferrari 4 speed gear box uses conventional gear oil.

I found a couple of bolts that were slightly loose at the overdrive, and tightened them up to see if they would stop the seepage. If there was ever a car that leaked as badly as an Italian car, it would be a British automobile, and a Laycock/deNormanville overdrive was living up to its origins!

There was one leak that was the oil filter screen of the Ferrari transmission, and it looked like the O-ring seal was leaking. Unfortunately, sliding out this filter assembly to replace the o-ring was impossible without first removing the overdrive unit of the transmission! Instead, I pulled the assembly out enough to clean the mating surfaces and put a smear of RTV sealant on the mating surface. Not my proudest moment, but worth a shot, just short of calling Tom to tell him we were pulling the transmission to chase an oil leak!

Draining a Vintage Ferrari gearbox is easy, but filling it is a little more involved. Access is tight from below, so Ferrari provided a small access door for the fill plug inside the car by the driver’s side of the transmission tunnel. The challenge was not to get oil on the new interior!

After filling tightening up all the bolts and sealing whatever I could, I filled both oil reservoirs up with appropriate oil and took the car out for a test drive. I was disappointed to see two drips forming at the base of the transmission. What initially looked like the leak was coming from the drain plug, was actually coming from the seam of the transmission housing. I could see this seam was sealed with a grey silicone, but it was obviously not working so well. This type of silicone usually works great, but I couldn’t see if a gasket was used as well. Having tightened all the bolts surrounding the case, there was nothing I could do to stop the leak just short of disassembling the transmission.

I stemmed most of the leaks, and my advice is to see how bearable the leaks are from the transmission. It’s not leaking bad enough to worry about and could take quite a long time to affect the oil level in the transmission. Tom can drive the car, but this final leak will require pulling the transmission to address.