: Front Differential Vent Leak ?



summitboy
01-01-12, 10:27 AM
I have a fairly new to me 2007 Escalade 125,000km. I noticed oil down the side of the vehicle here and there. I found it to be leaking from the front diff vent line of the driver side of the vehicle. It has been leaking for some time as the oil was caked all around the front left shock tower. I cleaned as much off as possible and monitored it for a while and it still was leaking. I thought maybe it was overfilled by the dealer i bought it from since the dealer i bought it from serviced the diffs on the purchase date. My mechanic checked it for me since the fill plug was seized on tight. The level was filled to spec. The vent tube is still leaking. Has anyone seen this issue before ? Any ideas ?

murphy
01-01-12, 01:19 PM
Could be filled with incorrect lube which may be foaming and venting out..

summitboy
01-01-12, 06:10 PM
I talked to a mechanic friend who has a Caddy expert mechanic lol and he said this is a very common issue with the AWD's. He said to drain and fill with Mobil 1 75W/90 full synthetic and then replace the vent line and put a loop in the line (trap) and start with that. He looked on some Caddy mechanics forum and said there are lots of ideas but no smoking gun for a fix. Does anyone else see this kinda leakage out of the line ?

murphy
01-01-12, 06:19 PM
Never in two ..'07-'09

hcvone
01-03-12, 07:01 AM
The only time I saw this was from filling to high, let me finish, if the trucks fluid was changed on a lift it's best to get your diff filled until it comes out the top filler hole, then lower the truck with a pan under the diff and let the truck sit on the ground for 5 or 10 minutes, not all auto lifts are level and when you get diffs that take very little oil like our trucks having the truck level is very important. I see these trucks everyday, have had 8 of them since 2007, what you are seeing is not normal. Make sure there are no kinks or clogs in the vent line

summitboy
01-11-12, 12:50 PM
So i finally have found some time to take a look at this issue. I ended up talking to a service manager at CMP in Calgary about my issue. He claims the first thing to check is the tires. He said to mark all 4 tires with chalk straight down. On a level surface drive/roll the front left tire 10 revolutions until mark is facing straight down again. He then said to remark all 3 tires straight down, and then roll them mark to mark and measure the distance on the ground. He said if any of the tires are out 2-3" that is causing heat in the diff and can cause leakage out of the vent line. I guess it makes sense lol. My tires are all Bridgestones but are not all the same if you know what i mean. I'll check the level once more and confirm the fluid and take the vent line off and make sure its not blocked. Also ill do this roll test and see where its at. Any thoughts on this tire rolling radius test ? He claims if the tires are out they don't cover power train issues. ???

hcvone
01-11-12, 01:37 PM
So i finally have found some time to take a look at this issue. I ended up talking to a service manager at CMP in Calgary about my issue. He claims the first thing to check is the tires. He said to mark all 4 tires with chalk straight down. On a level surface drive/roll the front left tire 10 revolutions until mark is facing straight down again. He then said to remark all 3 tires straight down, and then roll them mark to mark and measure the distance on the ground. He said if any of the tires are out 2-3" that is causing heat in the diff and can cause leakage out of the vent line. I guess it makes sense lol. My tires are all Bridgestones but are not all the same if you know what i mean. I'll check the level once more and confirm the fluid and take the vent line off and make sure its not blocked. Also ill do this roll test and see where its at. Any thoughts on this tire rolling radius test ? He claims if the tires are out they don't cover power train issues. ???

That is true with any car/truck with a locking rear or all wheel drive, you always want to replace tires in pairs, but for it really to be an issue you would have to have say a brand new tire on one side and a REALLY BAD worn tire on the other side, and here is why I am not really buying it, the stock Bridgestone's are already "cut down" on tread depth. This is what you can do, measure each tire on the diameter and pair them together i.e. the ones with the most tread put on the fronts, the ones with the least put on the rears.

summitboy
01-11-12, 06:26 PM
I measured all the marks and one tire was out like 2" max on distance. I'm gonna change the fluid to Mobil 1 75w-90 and check the vent line. I'll match up the tires tread wise since there is two tires that have a slight difference in wear. Go from there i guess.

hcvone
01-11-12, 06:45 PM
I measured all the marks and one tire was out like 2" max on distance. I'm gonna change the fluid to Mobil 1 75w-90 and check the vent line. I'll match up the tires tread wise since there is two tires that have a slight difference in wear. Go from there i guess.

That is a big difference, that much could be causing your problem for sure, you may have to get a pair of tires because that much difference could easily ruin a rear locking diff, the front is open and you will get away with it minus the fluid overflow problem for a long time, but this can and will cause damage over a long period

Naf
01-12-12, 12:56 AM
You may also be low on fluid, if you have ether overfilled or underfilled you will get the same results.