Hi All
I have recently picked up an 84 Corvette with original crossfire and a doug nash 4+3. The plan is to work on it with my son and make it a daily driver. Corvettes are not that common in Australia so I will probably have to do most of the work myself.

Anyway ive been gradually fixing the cars issues and it has been getting better and better. The other day i went down to the garage to be confronted by a large puddle of oil. The the oil was dripping down the back of the engine and was also on the top of the crossfire inlet manifold.

I read in these forums that it could be the oil pressure sender so I have removed the wiper motor and the distributor to have a better look. The oil pressure sender and switch look dry and I can’t see anything obvious. I thought it might be leaking out of the rear of the manifold and I noticed that a couple of the bolts were not tensioned up correctly so I touqued them up. It looks like oil is tracking up the choke cable (I thing that’s what it is) and depositing on top of the manifold then dripping back down.

my question is, would the oil under the inlet manifold be under enough pressure to cause this amount of mess or am I missing something?

Thanks for reading.

Hi and thanks for your reply.
I figured that I would be able to find the leak as there was quite a bit of oil, but its looking like I might need to go down the dye and uv route.
Regards Greg

Thanks Mate (looks like you have the Aussie vernacular down pat)
I actually have a Renegade intake manifold to put on but I didn’t plan on doing that just yet. The plan is to rebuild the crossfire at some point with new heads and cam and the Renegade. I bought the Renegade now because I don’t imagine that performance parts for a crossfire will be around forever but l like the idea of keeping the crossfire arrangement. Actually I think its kind of cool.

I’ve owned a few V8s over the years and removing the valley cover was quite easy, however there’s a lot less space under a C4 bonnet so a bit tedious might be an understatement haha.

Regards Greg

Hi Roy
I just posted a lengthy reply and got some message to say the the posted needed moderator approval so I guess it will appear in the fullness of time.

You also asked about mileage, the odometer read 106 thousand miles but who knows.

here is a picture of the mystery cable

Yeah I know of the L98 TPI engines, interestingly my SS commodore has an L98 as well but it is a gen IV and nothing like the 80s corvette engine.

I did some more chasing of that leak today. I’m pretty sure the oil is coming out of that TV cable. I gave it a good clean put the distributor back in and took it for a spin. Oil continued to drip out of the cable for about an hour. I have a Doug Nash 4+3 so is that Cable connected to the T10 or the overdrive unit O/D unit I assume? The oil coming out does not look like Dextron (red) so I hope it’s not connected to the O/D unit.

The previous owner told me he change the gearbox and O/D unit oil before I picked up the car. He owns a transmission shop so hopefully he knows the correct oil to use.

thanks again for your help Roy. I wonder what happened to the first reply I sent you? I guess it will show up at some point.

I thought that initially and thus I pulled out the distributor and the windscreen wiper motor for a better look. They certainly pack a lot of stuff into a tight space. This is my first Corvette and I can’t believe how awkward it is to work on.

Those TPI L98s do look cool though.

Regards Greg

Well I still don’t know what happened to my original reply. So here is a quick summary of what I said.

Avitar: When I uploaded it I noticed it was upside down. I figured you guys would get the joke so I left it that way.
FSM: I have the GM shop manual and the elecrical trouble shooting guide are they the two you are talking about? I have always tried to get the GM shop manual for the cars I have owned. I think the old ones were a bit better though.
84 Corvettes are cool: Yep I like the crossfire set up and I also like the Doug Nash 4+3

So I’ve been looking in the FSM and I can see where the throttle valve cable connects to the O/D unit. I guess I will crawl under tomorrow and see what I can see. I am puzzled because the oil is quite clear but if I had to give it a colour I would probably say gold. I guess there are other colours of transmission fluid but I would have expected red. It is quite thin it could be transmission fluid.

On my last adventure under the car I found a plugged hose that had a small amount of red transmission fluid in it. I assumed that someone had added this hose to make it easier to fill the trany. I plugged it more effectively and secured it out of the way. I’m worried how that maybe it was a breather pipe and I have plugged it up. Incidentally the overdrive does not work currently, the light comes on but it doesn’t change gears. I figure it is the solenoid or the pressure switch because electrically it can’t be anything else. It also looks like the solenoid had two pins but one is broken off, I could be wrong because I cant find a photo of one and ther doesn’t seam to be a loose wire. Anyway that a side line.

Thanks again for your help
Regards Greg

Maybe haha

Yep, you got it right!

Ok Roy you get the chocolates. I crawled under the car today and chased that pipe, sure enough it was a breather. The O/D unit had a light smear of oil all over it. It was dry last time I was under the car so I guess pressure and oil has been trying to escape where ever it can.

So I unplugged the pipe and oil stopped coming out of the TV cable almost instantly. So that mystery is solved.

This car has many mysteries partly because it has been converted to right hand drive and partly because there has been 34 years of opportunity for any old hack to bastardize the wiring and plumbing.

Colour color haha. It’s a bit weird in Australia we have cultural inputs from both England and the US plus of course our home grown quirks. So we are a country that loves V8 cars and not funny little British ones. We adopted the metric system in the seventies but most people still use PSI for pressures but kilometers and Celsius. (I find that a bit annoying on the corvette dash).

Hi Whalepirot
i look forward to calling on you expertise some time in the future but for the time being I think I’ll leave the Doug Nash alone. The O/D looks a bit like a powerglide I use to own only it have a drain plug.

Yep no worries I’ll take a couple of pics and post them. I warn you now she was prettier in her youth. Someone did a quality restoration on it about 25 years ago probably when it was imported and RHD converted. Most of it is there but it’s definitely a fixer-upper.

Cheers Mate
Glad you liked Sydney I was born there and lived there as a kid. I’ve lived most of my life in Brisbane or BrisVegas as it is affectionately known, it about 600 miles north of Sydney. (North is warrner in Australia) the climate is similar to Miami. I’ve been to the west coast of your beautiful country a couple of times and last year my wife an I visited NYC and loved it.

I’m very aware that the O/D unit should have Dextron and hypoid (I guess) in the super T10. This oil colour is a puzzle to me. The guy I bought the car off owns a transmission business and he told me he changes the oil in both boxes. He was well aware that the O/D unit was effectively an auto so I can’t imagine that he would have put the wrong oil in it. Although it is not red it is quite thin like transmission fluid. He also told me that he never had the overdrive working so it could have been broken for years.