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Tahoe & SuburbanThe power, space, and brutal towing ability make the Tahoe and its longer sibling, the Suburban, arguably the best full size SUV's on the market today.
Hi all, I have been having this mysterious oil leak on my 07 Tahoe, car has ~262K miles on it. Earlier this year I was changing the oil and saw fresh oil all over the underneath of the vehicle. Mostly covering the front sway bar, the side of the oil pan where the oil filter goes and what I now know to be as the oil cooler block off, and the bottom of the transmission bell had fresh oil on it.
First thought was the main seal...I was out of town at the time and had a friend of mine take a look. He had a little camera and put it through the opening in the trans bell housing and all is dry in there, so its not the main seal. It wasn't coming from the oil filter. So he decided to replace the oil cooler block off. It seemed to have stopped the leak, until yesterday when I was doing the oil change and saw the mess once again.
Assuming its not the oil block off gasket, btw, the old oil block off gasket from GM had a rubber seal built into the metal gasket, the new GM gasket does not have the rubber seal on it, so my buddy put RTV on the gasket, I'm hoping this is ok to do?
But anyways, assuming its not the oil block off gasket, my thoughts are possibly the oil pan gasket? If not the oil pan gasket, are there any spots up higher in the vicinity of the area where I'm seeing fresh oil where the 5.3L engine is prone to leak engine oil from? I feel like I remember reading somewhere that the oil sending unit is at a position up higher at the back of the engine and tends to leak? I may be wrong about that.
Its a tight fit under the car and the driveshaft is in the way that I can not see or even get a hint of where the oil might be coming from. It also doesn't help that my vertigo bothers me after laying on my back under the vehicle, then I just get frustrated and say to heck with it, lol.
I would scrupulously clean the underneath side of oil and then drive it for a while and then check to see if it's more obvious where it's coming from. Since it seems to be coming from the front to the back then I would suspect it's coming somewhere up front.
It might leak down the back of the crankshaft pulley and then get slung by the fan.
You could throw some baby powder against the engine and that might help you locate fresh oil seepage.
I don't know what kind of RTV was used, but if GM stopped using a rubber seal on the block off part, they probably have a reason for it. Maybe a paper gasket would do a better job of sealing the area, if the leak turns out to be originating there.
It might leak down the back of the crankshaft pulley and then get slung by the fan.
You could throw some baby powder against the engine and that might help you locate fresh oil seepage.
I don't know what kind of RTV was used, but if GM stopped using a rubber seal on the block off part, they probably have a reason for it. Maybe a paper gasket would do a better job of sealing the area, if the leak turns out to be originating there.
Pictures would help.
Thanks for the suggestion! I'm pretty sure the leak is not coming from the front of the engine. Its either originating from the oil cooler block off or somewhere above it, I feel.
I would scrupulously clean the underneath side of oil and then drive it for a while and then check to see if it's more obvious where it's coming from. Since it seems to be covering from the front to the back then I would suspect it's coming somewhere up front.
I did clean it pretty well with brake cleaner. What I really need is a good camera like a plumbers camera to snake it past the drive shaft and up and above the oil cooler block off.
The guy who replaced the oil cooler block off plate gasket suggested I put some dye in the engine to help locate the leak, but I'm not comfortable putting dye into the engine oil, not sure if thats a good idea or not, lol. The leak is already hard to pinpoint now b/c I cant see the tree through the forest, lol. Then I'll have to go buy a blacklight and the tiny camera, lol.
You can get an endoscope from Wish.com very cheaply. You can plug it into your phone and see whatever is at the end of the scope on your phone.
Thanks for this info, I had no idea that was a thing! lol!
Originally Posted by tech2
post some pictures
So I brought the car in to the shop that rebuilt my rear diff. I trust them, they do good work, and are honest folks there. So they got the car up on the lift and called me into the garage, the leak reared its heads, but was still hard to place the source. Still was mostly coming from where the oil filter sits and the oil cooler block off plate it. So the tech got out a mirror and flashlight and we both started to snoop around, and it seems that there is wetness along the top rail of the oil pan where it mates to the block, on the driver's side of the oil pan, which would make sense why I'm seeing most of the oil around the oil filter area and the oil cooler block off, bc when driving forward, the wind is going to blow all that oil back towards the area where I'm seeing the oil mostly, UNLESS there is an area that is right above the oil pan that is know for oil leaks, which I'm not knowledgeable about. I think the only area above this section of the oil pan that can produce leaks is maybe just the valve cover? I'm not too sure
But, they cleaned the area up again really well, and I just left the car with them overnight so they could drive it and let it run to catch the leak as soon as its happening, but I called this morning and its dry as a bone!! WTF! Aint this the way?! LOL! I should've just drove it home from their shop and go back there this morning to help put miles on it so the leak will show, but traffic is terrible from my house to their shop in the morning and I did not want to be stuck in that mess again for a second day in a row.
Sorry I couldn't get pictures with the car up in the air, I didn't want to take too much of their time bc they were busy as usual.
So just an update, after the shop took to time to drive the car periodically throughout the day yesterday, they said they did see some wetness coming from the top of the oil cooler block off plate. They removed the plate an checked it, according to them the plate was slightly off from being flat. So they put it on a belt sander and made it flush again, then put a new gasket with sealant as well. After they did that the did continue to drive it around every other hour and let the car idle, and it has remained dry. They didn't charge me a penny for all the babysitting they did with my Tahoe, and driving it and then putting back up on the lift to check the leak, then take it back off the lift and let it sit, then repeat that process multiple times throughout 2 days...I did bring them 2 large Papa John's pizzas when I showed up to pick up the car. Its a blessing when you find an honest repair shop these days for sure.
Im goin on a trip about 400 miles round trip, so if its going to leak again it will def. show up during this trip. Finger crossed its fixed! If the leak shows up again, I think the only next logical thing is to replace the oil pan gasket...
Last edited by Typerod; December 22nd, 2018 at 6:59 PM.
So I have driven the car about 170 miles since they looked at it this past Thurs and Fri. I got under the car this morning to check on it, and its still leaking, but I feel its not as bad. So after taking these pics I feel even more confident its the oil pan gasket. So I feel there were two leaks one bigger leak from the oil cooler block off plate, which is now fixed, I'm confident to say, and the 2nd smaller leak is from the oil pan gasket.
In the pics you will see above and slightly left of the oil cooler block off, where there is a slight curve inward on the oil pan where it mates to the bottom of the block, you may notice this spot a more wet than the rest of the area along the oil pan. This would make sense that I see oil dripping down from once it gets near the oil filter.
Any other suggestions are welcome! Thanks!
Happy Holidays to all! View from directly under vehicle..as you can see where the drips are resting, this will coincide with the freshly wet area in the next picture. View from the left front wheel well Zoomed in pic from left from wheel Zoomed in pic from left from wheel
December 15th, 2018, 10:33 AM
2007 Tahoe - can't find source of oil leak
