jwmezzanotte

Conversion on my car (ford 302) was done quite a few years ago (1994 i beleive). Ive got an oil leak on the back of the motor, between the engine and transmission.
If i park the car and dont move it for a week, which happens quite often, i get an oil spot in my driveway about 2" across. If I take the car for a drive and park for about an hour i get a few drops in that time. As far as i can tell the car doesnt burn any oil, and it runs very well. I keep a close eye on the oil level, it doesnt seem to be leaking large amounts. (btw, how many litres are Ford conversions typicaly filling with during oil changes?)

Would this most likely be the rear seal? Reading online ive learned that these engines can also show leaks in this area from the flywheel bolts if they werent sealed properly, and from the back of intake gasket. Any thoughts on finding for sure where this leak is coming from? Any other possible leaking points at the back of the motor?

Car has about 110 000kms on it, the engine is around the same year as the car so i would assume that its got similar mileage. The previous owner replaced the transmission with a rebuilt a couple years ago, so im hoping there isnt a leak there, any easy way to tell?

Thanks
John

ps How come the damn work truck never leaks oil instead of my car??

chpmnsws6

Leaking rear main seals are common on the 5.0's

chpmnsws6

http://www.fordmuscleforums.com/all-...l-install.html

Good thread with a few pointers

jwmezzanotte

Thanks for that.

I'm pretty sure its the rear seal. Never had a 5.0 engine before but ive read a few times now that there are rear seal issues.
Going to leave it for this winter, dont want to take the car apart during the good weather.
Anything else i should look at while its apart? I plan to do the clutch since its most likely got oil on it by now.

Also any tips to make it easier to get at? Any tricks or ideas to help reach the transmission bellhousing bolts?
I'll get to it one way or another, but thoughts from someone who's pulled the transmission on a 302 miata would be appreciated.
Thanks again

jwmezzanotte

More reading online, checking a few other things.

I had about a half litre overfilled when i did my last oil change, brought it back down to the full mark on the dipstick. What volume of oil are other 5.0 miata's using? I would imagine its less than stock since the pan was modified?

Next i checked the pcv valve. (that is a joy to get at in these cars) It rattles the way the haynes manual said it should, and the hoses seem okay no cracks etc. How snug should the grommet fit into the lower intake? On my car its REALLY loose, it drops in with hardly a push and seems like it would easily pop out.
Looked a little closer with a flashlight, the top of the lower intake has some casting holes filled with oil, (a couple small depressions, like a pencil eraser are full of oil) and there is quite a bit of oil all over the top of the bellhousing. Its wet to the touch and it looks like clean oil. (just did an oil change)
I'm going to replace the grommet and the pcv valve just in case (anyone know a source for them?)
Could this possibly be leaking enough oil to make it look like a rear seal leak? Anyone else experienced this?
I could maybe get in there to get a picture, but its pretty tight back there.

thanks

MRM331

If you do have to take the trans out you'll find it easier than doing the same job on a stock Miata. There's no PPF to worry about and the trans separates from the bell housing making getting at the bell housing bolts a breeze. The only thing you want to be aware of is that once you remove the trans crossmember the engine/trans assembly will tilt backward. Most likely the driver's side head will rest against the firewall giving you just enough room to get at those upper bellhousing bolts. Before you let the engine tilt back make sure that nothing (like the clutch hose) is in line to get crushed between the head and the firewall.
-Jason

jwmezzanotte

I'll keep that in mind, i was hoping it would tilt back a bit somehow.

Ive noticed since i made sure the pcv valve was in place, and lowered the oil level to the full mark on the dipstick that my oil leak has almost disappeared. Just a single drop after parking for a good hour, compared to the 2 inch circle spot i was leaving before.
Still think i have a rear seal leak, though not nearly as bad as i figured.

jwmezzanotte

Another issue i have with the car is some vibration, starts around 150km/hr and gets much worse afterward.

When the car is in 4th gear the vibration is minimal, 5th gear is worse, and if push the clutch pedal in at around 160km/hr and coast its almost scary. The dash, and especialy the center console and shifter vibrate so much that its visible, nevermind the noise it makes. Anything below 150km/hr the car is smooth and solid feeling.

I dont often worry about it because i just dont drive at those speeds, but I do wonder what it could be.
Driveshaft not balanced or damaged?
Maybe the engine/trans and diff are not aligned well enough?

thanks
John