EGR Tube vs. Manifold Leak

[Cincodemustache]

Mud - any pro tips for diagnosing or differentiating an exhaust leak at the manifold vs. on the j-tube? This is on a 60.

I suppose I’m trying to save myself the aggravation of tearing everything apart if there is a fool proof way to rule out the manifold.

 

[3_puppies]

look for black marks, exhaust trails.

 

[Spike Strip]

Smoke test.

 

[OSS]

If the stock EGR down pipe that bolts to the manifold is still being used, it's gasket is likely toast and is leaking. Change that gasket first and see if the sound changes. If no change at all - manifold.

 

[Cincodemustache]

Thanks everyone, I can see a new gasket on the manifold. I’ll bet the PO didn’t do the EGR so I’ll try that first.

 

[DFXR]

I was wondering the same thing, so i ran a shop vac in blow mode thru the exhaust pipe, and could feel air escaping at the manifold rather than the j pipe. Engine off of course, and cool enough to tape the vac hose to the pipe for a tight seal. You'll also want it cool enough at the manifold to get your hands up in there to feel for air flow.

 

[nfranco]

I was wondering the same thing, so i ran a shop vac in blow mode thru the exhaust pipe, and could feel air escaping at the manifold rather than the j pipe. Engine off of course, and cool enough to tape the vac hose to the pipe for a tight seal. You'll also want it cool enough at the manifold to get your hands up in there to feel for air flow.

This, combined with a spray bottle with soapy water in it is useful to find leaks.

 

[Cincodemustache]

I was wondering the same thing, so i ran a shop vac in blow mode thru the exhaust pipe, and could feel air escaping at the manifold rather than the j pipe. Engine off of course, and cool enough to tape the vac hose to the pipe for a tight seal. You'll also want it cool enough at the manifold to get your hands up in there to feel for air flow.

Winner. That sounds like the ticket.

 

[Cincodemustache]

Update: The j tube was a little loose where it connects to the manifold. The two bolts tightened fairly easy with what seemed like a 700 foot extension from below the truck. Didn’t want to crank on them too much for fear of snapping the studs. Exhaust leak noise was 50% better.

I’ll see if I can sneak a new gasket on there in the future. That heat shield looks to be in the way for sure.

How many ft lbs can I torque those 12mm bolts on the EGR to manifold flange? Thanks everyone

 

[OSS]

In my experience, it's easier to remove the rear heat shield (if the bolts haven't seized) than trying to replace that EGR down tube manifold gasket with it in place. I'm not sure it's possible- that's why I remove (and replace) that heat shield. Removing the heat shield is a project in itself- but believe me - it can be removed (done it plenty of times).

Do NOT use a torque wrench tightening those little two 12mm flange nuts that screw on to the studs. The studs have fatigued from heat cycling and CAN shear off with too much torque.

The spec for 12mm nuts is 12ft-lbs, but the safest way to tighten them up is by using a 3/8" ratchet with ONE hand and tightening "wrist tight" by twisting your wrist (not pulling on a braced handle).

The nuts are easy to check with the heat shield on, so you can check them again in the future to be sure they're "wrist" tight.

With that poor design of the EGR down pipe bolted to the manifold, torquing the nuts extra tight doesn't accomplish anything good.

 

[Cincodemustache]

In my experience, it's easier to remove the rear heat shield (if the bolts haven't seized) than trying to replace that EGR down tube manifold gasket with it in place. I'm not sure it's possible- that's why I remove (and replace) that heat shield. Removing the heat shield is a project in itself- but believe me - it can be removed (done it plenty of times).

Do NOT use a torque wrench tightening those little two 12mm flange nuts that screw on to the studs. The studs have fatigued from heat cycling and CAN shear off with too much torque.

The spec for 12mm nuts is 12ft-lbs, but the safest way to tighten them up is by using a 3/8" ratchet with ONE hand and tightening "wrist tight" by twisting your wrist (not pulling on a braced handle).

The nuts are easy to check with the heat shield on, so you can check them again in the future to be sure they're "wrist" tight.

With that poor design of the EGR down pipe bolted to the manifold, torquing the nuts extra tight doesn't accomplish anything good.

Thank you. This is exactly why I ask before flying in there and doing some damage. Appreciate the guidance!

 

[Cincodemustache]

Update: it’s not the j pipe to manifold. Shop vac test tells me it’s leaking at the firewall side of the manifold - bolt is tight. Can’t see much else due to the heat shield and I’m not ready to start taking parts off at 7pm - I have beers to drink instead.

Manifold will be well above my skill level so I’ll have to be resourceful getting this repaired.

Thanks everyone.

 

[Seth_O]

Update: it’s not the j pipe to manifold. Shop vac test tells me it’s leaking at the firewall side of the manifold - bolt is tight. Can’t see much else due to the heat shield and I’m not ready to start taking parts off at 7pm - I have beers to drink instead.

Manifold will be well above my skill level so I’ll have to be resourceful getting this repaired.

Thanks everyone.

I just did the manifold on mine. It's not that tough, just be sure to take pics and label vacuum tubes (if you've got them.) It looks really overwhelming and daunting, just take your time and clean stuff up as you go. It all just bolts on and off.

Some parts require a little patience, and there are a few order-of-operations issues, but it's not that bad.

Regardless of what you do, good luck.

 

[Dixon Santana]

At this point I can pull the manifold combo off in my sleep. In reality I have given up on the oem manifold (replaced gaskets 3 times already within 6 months) and am currently waiting for a set of Man-A-Fre headers to come in because I don't want to deal with exhaust leaks while at SAS in august, they are on back order so in the meantime I am dealing with the occasional puffing out the egr outlet on the exhaust.
It really helped the first time I removed the manifolds to have a pdf of the emissions manual.
Good luck!

 

[Cincodemustache]

I just did the manifold on mine. It's not that tough, just be sure to take pics and label vacuum tubes (if you've got them.) It looks really overwhelming and daunting, just take your time and clean stuff up as you go. It all just bolts on and off.

Some parts require a little patience, and there are a few order-of-operations issues, but it's not that bad.

Regardless of what you do, good luck.

Thank you. I have a friend who is a former Toyota MDT and he is gonna teach me a valve adjustment and timing in a few weeks. In a perfect world I’d like to find a used manifold combo, check the horns and heat riser then have them machined and ready to bolt on that same day we are already working. Pipe dream, but what the hell...better to have a helping hand and get it all done in one shot. The search begins...

 

[DFXR]

Thank you. I have a friend who is a former Toyota MDT and he is gonna teach me a valve adjustment and timing in a few weeks. In a perfect world I’d like to find a used manifold combo, check the horns and heat riser then have them machined and ready to bolt on that same day we are already working. Pipe dream, but what the hell...better to have a helping hand and get it all done in one shot. The search begins...

Used combos are out there.... post a "want to buy" message in the parts classifieds and you'll be surprised at what comes up. I had a couple folks offer combos for 2-300 bucks. They would still need to be machined, of course.

 

[Cincodemustache]

Closing the loop on this thread...replaced the whole assembly with a reman unit that was totally rebuilt and machined flat (money well spent!). All new oem gaskets for everything in the exhaust system in the engine bay and now I can finally drive without that wicked ticking. Threw on a new carb insulator plate as well.

The intake was definitely leaking too, I have to adjust the carb tonight as I had adjusted it before to compensate for the extra air getting sucked in at the intake manifold leak.

Thx mud!

 

[SteveH]

Sounds like you did it right! Check the manifold bolts from time to time, as they may get loose, and if so, they will take out the gasket again. Also, check the carb nuts, too.

 

[gregnash]

Was going to say that the other process/solution people have used is doubling up on the manifold gasket since these manifolds are a #$%^* to have machined properly (finding a good shop to properly do is the issue). Glad you were able to get it taken care of. One more thing that is on my list of things to correct after my head rebuild.

 

[DFXR]

Congrats to you. I just did the same thing.

AAAAND.... I still have a tick.

J-pipe gasket, I think. You can only imagine my joy.