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Intake Manifold Thermal Gasket Discussion 4g69

31K views 445 replies 35 participants last post by  trevroar 
#1 · (Edited by Moderator)
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#371 ·
I did change the order to:
IM > Thermal > OEM Gasket > TB
... same issues.
Would the gasket placement of the "sticking out" part be an issue. It's currently closer to the front of the car instead of towards the driver.
 
#374 ·
Swapped the gasket positions so the tip is now sticking out on the top but towards the driver instead of towards the front of the car. Tightened it as far as I could. Drove it and it's still whistling. A little less now but still there.

The only thing left I think is the sealant. You guys use the TB sealant?
 
#375 ·
copper gasket. mine does it though. so. not the sealant. idk what to tell you man. sucks but you sound Turbo'd at least lol
 
#377 ·
Hey guys try just using the thermal gasket. I haven't tried just because I'm waiting on my new TB to come, upgraded. And the fact that I just bent mine back in shape.

I was talking to GT fab, he said most of his customers install them without the oem gasket. So give that a try. I'll be doing it tomorrow since I'll have my TB then.
 
#380 ·
So if anyone knows, I haven't tested it but I received a ses code. I put on a Galant TB and the spacer. I'm getting the whistle but its only about 30-40% throttle any above or below it goes away. But it really doesn't seem like I have a leak, I sprayed some carb cleaner but it never got sucked in. (What I did to test for a leak before)

Its P2195-Stuck on Lean. And I want to say it was Bank one Sensor one. Is it really that big of a deal?
 
#382 ·
Any SES light for the front o2 sensors is going to be a big deal (bank 1 sensor 1 or bank 2 sensor 1) Try removing the thermal gasket, and reset your ECU and see if the problem returns.
 
#381 · (Edited)
Alright guys, I got around to at least installing my throttle body gasket today, and I even tried double gaskets and I still got the whistle. So, I did a little investigative work on finding out why and how to stop the whistle. I can assure everyone right now that the whistle isn't cause by a leak. Its caused by a flaw in the thermal gasket, simply because it was based on the OEM gasket. We all should feel pretty dumb right now, as we all rushed into installing the gasket with out looking at it before hand. Let me quickly sum this up with some pictures...

Take a look at this pic, this is how the gasket sits on the GS throttle body. Notice how the gasket center is about 1/8" larger than the throttle body opening. What happens when we install the gasket, we now have a 1/8" space between the throttle body and intake plume so when the throttle body opens we get the whistle noise similar to when you blow air over the top of a soda bottle.



So here's the flaw in design (I blame Mitsubishi). The OEM gasket for the GS throttle body is the same gasket used for the larger GT throttle body, which aren't port matched to the throttle body.

Ok, here's a solution for those of us who do not have a GT throttle body, and have the whistle. All I did was fill in the 1/8" gap with some silicone gasket maker, and guess what, no more whistle.

Here's what you do:

Overlay the gasket on the back of the throttle body, and hold it in place with the four bolts.

*** EDIT****EDIT**** The gasket IS NOT port matched for the GT throttle body. It will however work, but expect the same gap issues as the GS
*** EDIT****EDIT****



Next, get your gasket sealer and fill in the 1/8" space. I made a mess of it, but just let it sit for about a half hour and then clean off the excess with some rubbing alcohol.



After I cleaned it, I let it set for another half hour before I installed in on to the car, the sealant will hold the gasket to the throttle body.
Here it is all cleaned up. The tightening specs for the four bolts are ~21 ft lbs. If you don't put in enough sealant, you still may get a whistle. If it does whistle take it back off and just add a little more sealant, let it sit for about an hour more, and be sure not to gunk it on too much so you suck some into your motor or disrupt air flow.



Not sure what the other gasket is going to be like for the intake manifold, but will let you all know when I get to that in a few weeks.

Thanks for reading yo!
 
#383 ·
Awesome write up!! I wish I would've seen that earlier when I installed it before work again lol.

But I reinstalled the gasket and put a crap ton of sealant on. So far after 30 miles of driving and letting it idle for 15 mins no SES light :wub:

If I get one around 80 miles or so I'll know its just my cat code. But I'll still check it just in-case it isn't.

But I'm wondering, we should probably do this for the Intake Mani one also.
 
#401 ·
Awesome write up!! I wish I would've seen that earlier when I installed it before work again lol.....

....but I'm wondering, we should probably do this for the Intake Mani one also.
I took my manifold off today, had a look at the lower thermal gasket to see about possible space, and the answer is no. The thermal gasket is the exact same size as the ports on the the head. So there should be no issues at all with the lower thermal gasket.

UPDATE: GT Fab got back to me and they will me making appropriately size TB gaskets for us. My inclination is that they will be shipping these out for to those who both. Stay tune din the mean time.
Read this just in time, I'm currently porting the lower part of the manifold and was actually thinking of porting the throttle body end first. Are they going to provide these at no cost, or should we expect some cost?

I took a few pics of my porting progress will get some on here shortly...
 
#384 ·
Noticed that also so I tried lining up with the GT tb (not installed) and still there's a small difference in size. Will take pics later.
 
#386 ·
Darkside's right.

So one thing we can all agree on is the gasket sealant will help.

Also what helps is not using the OEM metal gasket. One less gap to worry about.
 
#387 ·
Think we should advise GT Fab of this, they seem to still be making these and selling them on eBay. I'd be more than willing to buy one that is matched to the throttle body opening.
 
#388 ·
Anyone with a ported tb and intake manifold using the thermal gaskets?
 
#389 ·
Idk about this particular one. I know member meDave or tortool not sure which exactly. One of them has a ported IM with a GT TB running a RPW phenolic spacer and is code free. I also have the RPW spacer on and have nodes or whistles.

However the RPW spacer is a true phenolic
 
#392 ·
Two Things:

1. Spoke to GT Fab on the TB gasket sizing. They informed me that since Mitsubishi has used the same IM flange pattern for aeons that they have modeled the 4G69 Tb gasket off of an old DSM gasket. I'm workign with them to try and resolve this issue.

2. The IM gasket was cut off an OEM gasket that I sent them. The cut for that is very precise and pretty much spot on. Make sure you don't over tighten the those bolts during installation.

Since I initiated the group buy it's probably easiest that if you're having any issues at all let me know and I will report it to GT. No sense having a bunch of you call or email them individually.
 
#393 ·
Wow, im having this whistle noise with my RPW spacers also, thanks for finding out the prob yo, i just didn't give a dayum enough to look at it haha. +rep and +love
 
#394 ·
It's not a deal breaker if you only use the GT Fab thermal gasket especially at the price point offered to us. The whistle is just slight and rare and I might actually go ahead with the IM spacer install also.

But I hope since it's in direct contact with both the IM and TB, there won't be melting/heat-warp issues.
 
#395 ·
did that thing trev said today and it worked, woot!
 
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