Rear Main Seal Leak...
 

99 2.5L Auto Trans. Small leak of oil running down the drivers side of the oil pan. replaced the valve cover gasket as well, was thinking the next option was rear main seal considering the truck has 150k on it and when i changed the valve cover gasket i didnt see any oil on the side of the motor. was wondering if anyones had them done before on this motor and an approximate price? i know its a labor intense job so thats where most of my cost will be. dare i ask about bar's rear main seal leak? im not the kind of person to cut corners and im not too hip on the idea of leak repairs. any input would be greatly appreciate thanks in advance guys...

I recommend using some oil dye to confirm the leak. It's cheap enough to make it worthwhile and will definately point to the big leak that needs attention. Might not even be the rear main.

I like g_k50's dye test idea.

You add the dye to the oil, drive it some, then look for the leak with a black light, which makes the dye glow bright yellow/green, so the leak area should be easier to spot.

If it's the rear main seal & it's not too bad a leak, as you've said it's not, you might consider trying a High Milege crank case oil recipe, in the brand you like to use & see if that'll slow or stop the leak.

I've never has an occasion to use that, but some on this forum have tried Valvolene's High Mileage recipe & had good luck stopping a rear main "weep", so we have some feedback on that flavor high mileage recipe.

Most blenders have a high mileage formula & they have a kicked up ad pack that includes extra detergent/dispersants & seal conditioners, to slightly soften & swell old hardened seals.
So it might be worth a try & it's extra detergent/dispersants will also tidy up the engines innards.

Use a good quality oil filter that has lots of surface area, like a Motorcraft, or PureOne, so it won't likely get clogged up & go into bypass during the treatment, if you know the engine has deposits, from your recent top end valve cover gasket work.

IMO using a High Mileage formula oil is likely to be less risky to use, than an after market Top Treatment, who's recipe you don't know is compatible with the oils ad pack chemistry.

More thoughts for consideration, let us know how it goes.

Hi There. Thanks for these posts. They're helping me understand some things about my 96 b2300 leak that I'm seeing along the sides and back of my oil pan.

I'll try the dye, and the seal conditioner is worth a shot, too.

My truck is at 150k. Anyone know if using full synthetic oil might worsen a leak like this? I could switch to conventional, or a blend. I'm also using 5w30. Maybe a thicker oil should be used?

If something needs to be replaced (seals, etc), I'm in. But I want to take steps to discover what it is, and try to alleviate the leak if possible.

If youve been running synthetic its whole life its shouldent be harming it. However, I would try Mobil 1 10w30 High Mileage to see if it'll swell the seal enough to stop it.

If you havent ran synthetic the whole time go to Castrol 10w30 High mileage. Ive had good luck with it. It will take a couple oil changes for the full effect to set in though.

If your losing a lot of oil the seal needs to be replaced, but rear mains tend to weep.

Seeing as how you say the sides of the oil pan are showing signs of leaking, make sure your PCV valve isn't clogged up & not working, as that along with more blow-by from worn piston rings, can cause an over pressure condition in the crankcase & cause seals & gaskets to blow out, or weep.

If the PCV valve checks out & elevated blow by isn't a problem, check the pan fastners torque value & evenly torque them up to spec & see what happens.

Syntetic crankcase lubes aren't likely to help an oil leak problem, but a dino "high mileage" recipe, in the specified viscosity range might help, if the problem is caused by old, hard, shrunken, rubber seals & isn't too bad.

Consider trying a high milege recipe oil, rather than an after market "top treat" additive, that might upset the crank case lubes synergy, or over soften a gasket or seal & cause it to blow out.

More thoughts for pondering, let us know how it goes.

Thank you. I'll go read my book and look for info about the PCV valve and then go have a look. Good call on the high mileage oil. I'll replace mine tomorrow and see what I get.

here is apicture of the pcv it is right near the fuel rail. If you end up needing a new seal. the part is less than $20. depending on your locaton and who you get to pull the tranny I would guess that the most optimistic price would be $500
http://i1096.photobucket.com/albums/...g?t=1293447146

and check the oil sending unit i had a 2.3 just pouring the oil it would use 2 courts a day. i thought the rear main was blowed out and i put it on ramps and started it and sure enought it was coming from it on the 2.3 the sending unit is on the side of the motor just right under the intake hard to see and find. i hope this is ur problem lot easier fix than a rear main. but you need to replace ur pcv and check the oil sending unit. even if you gage is working right dont mean it ant leaking.

I'm starting to get a small drip off the bottom of my 2.3 just ahead of the tranny bell. It started about the size of a 50 cent piece. Did the dye and both me and the garage thought it was main seal, but in light of this thread I'm going to have another look at the sending unit. Mine has 125K on it and I thought I'd try Auto RX, since it is the only additive anyone seems to think has a chance of conditioning the seal. I am on round two of that with no luck and the drip has grown to about silver dollar size. Another reason to perhaps consider the sending unit. Interestingly, the Auto RX people say if you use their stuff you are not to use high mileage dino or synthetic. I assume their concern is too many additives. So I've been using plain old Valvoline 5W30.

Even if it isn't the main seal, I'm wondering if I should be kicking myself for not having a new one put in when I had the clutch done about 20,000 miles ago. The shop knew you always replace the slave cylinder when you drop an M5OD for a clutch, but they did not suggest doing the seal. I know it would have been cheaper since the tranny was down, but I'm not experienced enough to know how much more would have been involved.

if they replaced and or turned the flywheel and did not suggest a new rear main seal.....they are incompetent. the seal cost $10 and you need to remove the flywheel to replace it. about 30 minutes tops. autorx has you use dino because the additives in the other oils neutralize there "ester" additives. you can use Shell rotella T6......it is get great reviews and is a full synthetic.

It has been at least a year since I had that clutch done, truck does not see alot of miles since my son normally has it away at college. My best recall is they did not have the flywheel out-they checked it and said it was fine. I'm going to check the sender [and filter since I know now and then even though all I use is the Motorcraft FL1A they still can seep] but after that I'll have to think about what oil to use. Before used Valvoline high mileage-it has never run on a full synthetic. Whatever is better to slow the leak if I still have it. Whatever it is right now is still small enough to just babysit, in my view.

customstringer, your leak doesn't sound too bad, so when you finish with the ARX treatment, if it doesn't slow, or stop the leak, maybe then consider trying a "high mileage" recipe crankcase lube of your choice & see how it goes.

ARX says that if it's removing varnish between a rotating shaft & seal thats hardened, it might take a little while after the clean & rinse phase for the seal to rebound & seal things up. So the leak may increase a little after the cleaning & rinse phase, before it slows or stops.

Pawpaw thanks as always for your valuable posts. I'm on round 2 of the AutoRX, put in one dose per the spec on the bottle when the truck went back to college and a second similar dose when it went back at Thanksgiving. Maybe I ought to order another bottle to use when I change the oil before I send it back in Mid January. I know they say it can sometimes take a couple of treatments. If it has stopped I won't but otherwise from what you say it can't hurt and might help. I have one jug of straight dino left anyway-it was on sale so I took advantage.

Edit: On second thought the Auto Rx website says for higher mileage engines it may take two treatments and drip some after that, so I won't go with a third. But it does say stick with conventional only or the leak could come back. . .

I wouldn't use a "high mileage" recipe lube with the ARX.

If your finished with the ARX rinse phase & it hasn't slowed or stopped the leak, then maybe consider a "high mileage" crankcase lube & see how it goes.

If the oil change your about to do, is after the ARX rinse phase & things haven't improved, maybe a high mileage recipe is worth consideration.

Of course the real fix is to replace the seal, but maybe this can improve things & make it last long enough for a more convenient replacement time.

If it continues to weep, make sure that youngster is keeping a close check on the crankcase fill level!!!!