vacuum leak?

[SuperHO]

So I got overly ambitious yesterday and ripped the upper and lower intake off my 98 to clean it...



yeah...my new wife found out the sink can double as a parts washer. Just wait till I show her how well the dishwasher works. :woo-hoo:

Now in the process of all this, I gutted the secondaries and filled the holes with some high temp RTV. Slapped the whore back together, and she was VERY unhappy about running. Ripped it apart again, and the RTV had failed, allowing all sorts of imbalances. So I rammed the rods back in there without the butterflies, and now she runs, but still ain't happy. She'll either idle at around 600rpm or 3500...no where in between. When she revs up, there's a high pitched whistling sound coming from the vicinity of the LIM near cylinders 5 and 6 (front bank, first two on the left as you're looking at it). Now once you get out and get going, she runs like a ***** gorilla...however, thanks to the absurdly high idle at times, she'll be more than happy to cruise along at 45mph without even having to touch the gas. Now, with this whistling, I'm assuming a vacuum leak and gonna tear her back down again once I get feeling back in my fingers. Any other thoughts as to what this might be?

Also...anyone got any tips on reinstalling that damn plenum? Any way to make it easier?


I knew there was a reason I stuck to wrenching on gen IIs...:theyareontome:

 

[Silvapain]

Definitely sounds like a major vacuum leak. There are set screw holes for the butterfly shafts that are probably the source of the leaks.

Instead of RTV you can use JBweld, but you still need to let it sit for several hours before reinstallation. RTV takes a day for it to set.

 

[SuperHO]

dammit, that's what I forgot!!! them's the screws with the springs, right?

 

[SHOZ123]

There are two spots on the bottom of the LIM that need filled too.

 

[SuperHO]

yup...put the screws in, and it was still leaking. Turns out the gasket between the LIM and the head couldn't get a good seal. So I got back in there with a wire wheel and cleaned up ALL the contact surfaces, RTV'd the LIM to head gasket and slapped it all back together. Then, after putting the RIGHT bolts in the EGR valve, all is well! She's purrin like a walrus!! Thanks, ya'll!

 

[93rev2sev]

yep, sounds like a vacuum leak.

Oh wait...am I too late?

 

[SuperHO]

 

[Silvapain]

yup...put the screws in, and it was still leaking. Turns out the gasket between the LIM and the head couldn't get a good seal. So I got back in there with a wire wheel and cleaned up ALL the contact surfaces, RTV'd the LIM to head gasket and slapped it all back together. Then, after putting the RIGHT bolts in the EGR valve, all is well! She's purrin like a walrus!! Thanks, ya'll!

No need for RTV; next time, spray paint the gasket and let the paint tack up before assembly. The paint makes a great gasket sealer.

 

[Izzmo]

I've always been cautious about using paint. Not sure why, but it just doesn't seem .... right.

 

[SHOZ123]

I've used paint on all the gaskets I reuse. I've had the intake apart countless times and never a leak. What you definitely don't want to do is use RTV sealants. This may seal but is next to impossible to clean off when the next time comes.

With the new paint on the OEM steel painted gaskets, just make sure there is no loose old paint and spray away. I use a brass brush to clean the old gaskets and mating surfaces with.

 

[SuperHO]

meh, all things being equal, I don't see removing that LIM anytime in the foreseeable fututre anyway. No real reason to.

 

[38SHO]

yeah its Yamaha... motorcycles like it


check here, they sell all sorts of yamaha stuff, and a couple other sealant/adhesives

http://www.parkeryamaha.com/yamaha.aspx

;-)

 

[FlaSho]

Gorillas??? Apes??? Walruses?? A Tweety Bird Toaster???

Race wars in New Jersey?? A woman named John???

Nice job dude, I would be sleeping in the SHO if I did that!

 

[FlaSho]

"There are two spots on the bottom of the LIM that need filled too."

Paul, what are these holes? Air bleed or set screw lock points?

I missed THIS in my pull down....

It might be a source of vac leak for me...

THANKS