Throttle valve body leaking
jwelch1103
09-07-2007, 09:06 AM
Hello All,
I recently had trouble with my 2001 Impala 3.4L engine with 90k miles. Turned out to be a bad catalytic converter. Reading posts here helped alot in the diagnosis but the final conclusive proof was when a workmate (who is a "real" mechanic not a shadetree like myself) checked the back pressure in the exhaust forward of the cat and found it to be 60 psi! He told me he was surprised it even ran.
Anyway, I found out by reading the posts here about the faulty intake manifold gasket issue with this vehicle. My vehicle does have an oil leak but I am not sure where this leak is. Nothing serious as I do not have to top off the oil between changes, which is done ASAP when the cars computer tells me it is time to change the oil. Just enough to coat the engine.
It also has exhibited a low coolant message twice in the last two years or so. I have not seen any indication of coolant in the oil, i.e. nothing unusual on or around the oil filler cap or in the used oil. I changed the oil the other day and took a sample to send off to be analysed so I should know shortly whether this is a problem here.
I am writing today for any advice one may be able to give me. In the course of diagnosing the recent problem (the cat) the mechanic mentioned above hooked up his smoke machine (slick little machine BTW) to check for vacuum leaks. No "vacuum" leaks found but the throttle valve body did exhibit a leak where the shaft (that the accelerator cable is connected) passes through the throttle valve body casing. Since this is past the MAP sensor he recommended that I repair this. It seems to me that this leaking seal is not sevicable and I believe I have to replace the throttle valve body, can anyone confirm this?
Also, and this is working off this possibly incorrect presumption that the throttle valve body needs to be removed, I was considering doing the lower intake manifold replacement since I would not be too far from this procedure while doing this. I have read the sticky originally posted by Surrender and while the link posted therein by BNaylor is dead the info cited is available on the web and it is very informative. If anyone has any other tips or info to add please do. Thanks in advance.
Jim
I recently had trouble with my 2001 Impala 3.4L engine with 90k miles. Turned out to be a bad catalytic converter. Reading posts here helped alot in the diagnosis but the final conclusive proof was when a workmate (who is a "real" mechanic not a shadetree like myself) checked the back pressure in the exhaust forward of the cat and found it to be 60 psi! He told me he was surprised it even ran.
Anyway, I found out by reading the posts here about the faulty intake manifold gasket issue with this vehicle. My vehicle does have an oil leak but I am not sure where this leak is. Nothing serious as I do not have to top off the oil between changes, which is done ASAP when the cars computer tells me it is time to change the oil. Just enough to coat the engine.
It also has exhibited a low coolant message twice in the last two years or so. I have not seen any indication of coolant in the oil, i.e. nothing unusual on or around the oil filler cap or in the used oil. I changed the oil the other day and took a sample to send off to be analysed so I should know shortly whether this is a problem here.
I am writing today for any advice one may be able to give me. In the course of diagnosing the recent problem (the cat) the mechanic mentioned above hooked up his smoke machine (slick little machine BTW) to check for vacuum leaks. No "vacuum" leaks found but the throttle valve body did exhibit a leak where the shaft (that the accelerator cable is connected) passes through the throttle valve body casing. Since this is past the MAP sensor he recommended that I repair this. It seems to me that this leaking seal is not sevicable and I believe I have to replace the throttle valve body, can anyone confirm this?
Also, and this is working off this possibly incorrect presumption that the throttle valve body needs to be removed, I was considering doing the lower intake manifold replacement since I would not be too far from this procedure while doing this. I have read the sticky originally posted by Surrender and while the link posted therein by BNaylor is dead the info cited is available on the web and it is very informative. If anyone has any other tips or info to add please do. Thanks in advance.
Jim
taillight
09-07-2007, 10:15 AM
Yes you should replace the throttle body to get rid of the leak.
richtazz
09-07-2007, 01:17 PM
Welcome to AF!
That's a heckuva first post.
The coolant leak your engine is known for is usually an internal leak. It will cause the coolant to get in the oil, but does appear externally as well. It is due to the cheap factory plastic gaskets cracking at the coolant transfer passages between the heads and intake. Your oil sample will finger the intake. If you need to do the intake gaskets, the throttle body will come off with the upper plenum, so replacing/repairing it at this time would be a smart move.
That's a heckuva first post.
The coolant leak your engine is known for is usually an internal leak. It will cause the coolant to get in the oil, but does appear externally as well. It is due to the cheap factory plastic gaskets cracking at the coolant transfer passages between the heads and intake. Your oil sample will finger the intake. If you need to do the intake gaskets, the throttle body will come off with the upper plenum, so replacing/repairing it at this time would be a smart move.
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