Ok, so yesterday, i took my truck 2 the mechanic, and when they lifted it up, we all noticed that there is a leak on the bottom of the truck. The mechanic told me that it is a seal, somewhere in back of the engine, where the transmission and the engine meet. I asked how much it would be 2 fix it, and they told me $500, but he said that i shouldn't worry bout it now, cause it's not a major leak. Still, i don't like the fact of having my truck leaking anything at all. Do you guys think that this price is too much? He told me that the transmission would have 2 be taken off, and then get 2 the seals.

 

If its the rear main seal, yeah $500 is reasonable. Basically, either the engine or transmission has to come out to replace the rear main seal.

One thing though, check your oil pan bolts. I had a leak in my engine oil pan that I tracked down to loose oil pan bolts. I was so bummed because I thought it was a rear main seal too.

I tightened them down good and snug last winter, but now the leak is back. I'm now going to spray some brake cleaner into the holes to clean the oil out, then use some removable strength loctite to hold them in.

 

If your blazer is one of the 2wd standard shift blazers, and the rear main seal is leaking, I would get it fixed in a hurry. I had the rear main go bad on my 1982 Jeep J-10 and got motor oil on my clutch disc.... talk about bad stuff.... it made my clutch start slipping really bad, burnt the disc...... to make a long story short, i had to replace the rear main, clutch disc, pressure plate, throwout bearing, pilot bearing and bushing. . . . . However, if it is not a manual, I would imagine oil in an auto transmission could also screw some things up.... I'd have it checked if I were you.

 

If you have the auto tranny there are two seals that you have to be concerned with. Engine rear main seal, and the tranny front seal. Neither is good, but it would be better if it was the engine seal. If the oil is red, tranny, if black, engine. In either case, yes the tranny has to come out, adn while it is out, replace both seals. Plus they will have to replace the tranny dipstick tube seal, and depending on how they do it, the t-case to tranny seal. But in most cases you just use gasket maker there. Unless your going to spend the money for a new seal at the dealer, dealer only part.

 

Wait, im a little confused. U see, the thing is, that i was thinking that since im gonna pay $500 to have that seal replaced, i might as well, replace EVERYTHING that should be replaced so that i don't have to pay another $500 each time. Can u please list every single seal, or anything else that i should replace now, to avoid wasting another $500 again?

 

As far as what requires pulling the motor or trans to do, Tim hit on the main ones, but if they have to pull the motor, I would suggest replacing the oring seal on the engine oil pan while they have it out. The engine is required to be removed to change the pan oring since the pan is a structural member of the engine block.

But like I said earlier, you have to determine if it really is your rear main seal. If you pull out one of those black plugs in the trans bellhousing and see that the back of the flex plate is dry (ie no oil), then I highly doubt that it is your rear main. Then I would say that you have a situation much like mine where the pan bolts have loosened up and need to be tightened back down (which I have to repeat).

 

Ok how about we try it this way.

There are several places for oil to leak and :look" like it is the rear main seal.
1) Your mechanic listed the rear main engine seal, possible, yes.
2) Swart has mentioned the oil pan gasket, again a possibility.
3) Intake manifold gasket leak.
4) or it could be a valve cover (least likely), or something else on the engine, (again least likely).

You need to find the leak before oyu can fix it.
If it is the rear main seal?
You have to either pull hte engine or the tranny out. Tranny is easier and least expensive.
The only way to replace the rear main seal is to seperate the engine from the tranny. Then you have to take the flexplate off so you can get acess to the seal. Pics to follow.

Ok it took me a bit, but I had to take the engine out to get the pics. [8D]
In this pic you can see the big round shiny thing, flexplate. The kjob of the flexplate is to provide a place for the starter to start the engine (teeth on the outside edge). It also provides a place for the torque converter to bolt to the engine. 3 bolt holes about 2/3 the way out.



In this pic I removed the flexplate so you could see the seal. Shiny thing and you can see the bolts that hold the seal retainer to the block. You have to pry the old seal out. No way that is gonna happen with the flexplate in the way.


With me so far?
Since its easier to remove the tranny, and more cost effective. There is another seal in the front of the tranny that "should be replaced while you have the tranny out. Its the called the front seal.. The torque converter slides into it, and that seal prevents your tranny fluid from puking all over thet ground. It is an extremely critical seal. Once it leaks, you have very little time if any to shut the engine off. It will only take a matter of minutes for the tranny pump to pump your tranny dry. Can you say $1500 for a new tranny? Its a $5 part, get it replaced. Take no effort.
I took my tranny out to show you.
In this pic you can see the torque converter. Notice the three bolts holes, those bolt up to the flexplate.


Pic of the torque converter.
See teh shaft in the center. That part slides into the tranny pump. See the notches in the shaft, those engage the pump. The tranny front seal goes around that shaft.


In this pic I removed the torque converter. It slides right off. Nothing to unbolt, unhook or anything. It literally slides right off the input shaft of the tranny. Pop the old tranny front seal out, and tap in a new one. Its that simple.


Since you had to take the tranny out, you have a few other gaskets/seals you will need to replace. Tranny dipstick tube is one of them. And if tehy left the t-case attached your done, if not, then replace a seal betweent eh t-case and tranny. Which one will depend on where they seperated them.



2) Swart coverd that pretty well. I do want to add. SInce this is a 4x4 S10-Blazer, there is a solid cross member that runs under the engine oil pan. The only way to remove the oil pan is by removing the engine.
Pics of GM oil pans. The bottom one (black) is the standard GM 4.3L S-series 4x4 oil pan. It has the sharp drop due to the cross brace. The oil pan has to fit around the cross brace. The top pan came off of a 4.3L from a fullsize truck. Notice the stagger step? That pan wont fit between the engine and cross brace.


Ok, how about if I just lift the truck up an inch or so. Nope, you have to clear the cranksh

 

Yeah, woops... I forgot about the single piece case... The cast aluminum oil pan and the 2pc case came somewhere around the '96/'97 model years where they made the switch. Its pretty easy to tell the difference from underneith.