Vacuum leak help,(pictures)

[Larry610]

2003 3.8ltr

I had it to the shop today to diagnose the Service engine light. They found a vacuum leak right at the manifold.
There is a actuator that pulls/pushes a mechanical lever that comes out of the front of the intake manifold.
Mitsubishi says they want $1500 (cdn) for the intake assembly to fix!!

There must be another way to repair? has this happened to anyone else.




The arrow points to the source of the leak

[my.paj]

It must have the butterflies in the plenum, you can remove them and seal where the shaft comes out, search this in 6g74 DOHC

[Larry610]

It must have the butterflies in the plenum, you can remove them and seal where the shaft comes out, search this in 6g74 DOHC

Humm all I can find in reference to that was this, https://www2.pajeroclub.com.au/forum...ad.php?t=21089

Doesn't really say too much. I am assuming I'd have to dismantle the intake/plenum to do this.

what seal fails? is it a o-ring or lip seal?

[Tuba]

To clarify what was said in that linked thread, the butterflies are to change runner length. High RPM, short runner (like a motorbike), low RPM long runner. It is for torque down low and better performance up high.

If removing them leaves them in a state of long runner, you will only lose the high rpm gains of a short runner. If the other way round, you would lose low rpm torque. Based on comments removal causes no issues, its default setting will be long runners.

90s Falcons had log manifolds, they were long runners and mid 90s Ford gained performance across the board by using a snail style manifold with butterflies to change runner length.

Id just buy a good plenum from a wreck, or fix the one it it if you can.

[Gen3]

If it was my car , I would remove the plenum chamber , and remove the butterflies completely. you can seal the hole with a welch plug ( or core plug ).

what if you leave the plenum in place , disable the actuator ( by plugging the pipe ) , and then knead some hardening putty and squish it in around the bit where the shaft goes in?

[my.paj]

Humm all I can find in reference to that was this, https://www2.pajeroclub.com.au/forum...ad.php?t=21089

Doesn't really say too much. I am assuming I'd have to dismantle the intake/plenum to do this.

what seal fails? is it a o-ring or lip seal?

Try Google, I also found this http://www.4x4wire.com/mitsubishi/tech/lower_plenum/
I think its a brass bush or metal that wares out over time if you still want to leave it standard try search for the bush or you will have to get it made.

[psproule]

Just re-bush it. Any carby repair shop can do it. Although not too many of them around any more.

[dmenheere]

2003 3.8ltr

I had it to the shop today to diagnose the Service engine light. They found a vacuum leak right at the manifold.
There is a actuator that pulls/pushes a mechanical lever that comes out of the front of the intake manifold.
Mitsubishi says they want $1500 (cdn) for the intake assembly to fix!!

There must be another way to repair? has this happened to anyone else.




The arrow points to the source of the leak

did you ever solve this? Have the same leak.

thanks,

Dave

[dmenheere]

did you ever solve this? Have the same leak.

thanks,

Dave

pulled the manifold off and removed the shaft for the butterfly's. The seal at the actuator end was missing so I found an o-ring that worked. Seems to have worked ... no more vacuum sound and no more traction control/skid lights.

When the lights came on before I knew I had a P0171 and P0174 code ... lean on Banks 1 and 2.

cheers,

Dave

[Larry610]

Finally got around to tackling this. I want to share the pictures on how I fixed it.
I took on the problem with Dmenheere advice, and replaced the seal with an oring.

I removed the mainfold, which isn't that difficult, just tag/mark all the hoses you remove for easy install. the EGR pipe needs to be unbolted too, there is a steel gasket there...don't loose.
Some hoses are for fuel (return?), and coolant. these will leak when disconnected. I plugged them with bolts while the manifold was off.
(I did this without removing the butterfly's or shaft)

Here is the manifold on my bench. I have the actuator leaver assembly removed and the retainer bracket also.
Look on the 10:00 position you'll see a small hole, this is for a small roll pin, that I have also removed.
At this point you can carefully remove the bushing with a flat head screw driver



Here you can see that the original seal is missing!



I found a oring from a kit I have in the tool box. (kit is a standard kit you can find at any auto parts store)
I lubed it up and started reassembly
*Note, in hindsight I should have used a heat resistant oring! If it becomes a problem again, I'll have to source one.




One more thing to mention is the manifold gasket is a rubberized one. And mine stayed on the engine when the manifold came off. For peace of mind I used a light amount of high heat rvt sealant for reassembly.

[Larry610]

After a short test drive, the service engine light returned, and turned out to be a code for the catalytic converter issue.
The light did go out on its own during the past week

the vacuum code is gone, and the traction/stability lights are gone.

All is good again.

[Hardwaregrrl]

Thread from the dead I know.....curious if you removed the butterflies or kept them. I have this issue and before I tackle it I'd like to figure out if I should lose them or red loctitie them in? Thx!