Throttle body repair help

[ned032002]

I did a boost leak test and heard a lot of hissing around the throttle body so I started pulling on things to see where it was coming from. I found out that when I turn the throttle plate, the hissing pitch changes so I thought that was odd. Then when I pull out on the throttle plate (where the cable attaches...pulling towards the firewall) the hissing goes almost completely away but you can hear barely hear a little bit still but barely enough to worry about. So w/ some research I found out that the "O" ring at the end of the throttle plate inside the throttle body will occasionally wear out and cause boost leaks. I found in the VFAQ how to repair the bad "O" ring and how to fix the boost leak. I have just 2 questions:
1. Where is the air that is leaking, going to? I can't find on the outside of the TB where the air is escaping to. So where is it going?

2. Is the "O" ring that's possibly bad be the only thing causing the throttle plate to move side to side when facing the throttle body head on? Could something else be bad? I know that if the screws on the plate itself are loose then the plate will move also if the nut on the end of the shaft is loose then that too can cause it to move side to side.

Any and all help will be helpful w/ this repair. Thanks guys and please respond asap because I want to start the tear down tonight. Also what kind of grease do I put on the "O" ring to ensure proper function? I read in the faq that the guy used silicone grease, is that the same grease that is used on the end of spark plug wires and the same stuff they sell in those tiny packets at the register at Autozone?

[tfoti]

I just did this on my 90 while the TB was off. I wish I could answer both questions thoroughly but I would need it sitting here in front of me. But will give you a couple tips.

I don't see why it would move unless that nut was loose.

Just go ahead and pull it off as per the vfaq and mark up the green coiling spring and mark the TPS in relation to the TB itself, as I'm sure you read already. The screws that hold the plate on will be the biggest problem. I had to drill and re-tap both of them even with the right screwdriver bit. Mark everything GOOD.

The grease is called Dielectric grease and yes that's the stuff you buy in those small packets for spark plugs. Good luck.

[ned032002]

Originally Posted by tfoti

The grease is called Dielectric grease and yes that's the stuff you buy in those small packets for spark plugs. Good luck.

That's the grease I put on the "O" ring right?

[tfoti]

Yeah. The silicone base won't dry them out.

[ned032002]

Thanks a lot Tim (in signature?) going right now to pull TB out.

[tfoti]

Yeah thats me. Good luck and thank the DSM gods you don't have a 90 TB.

[ned032002]

Alright good news so far...got the new o rings installed and everything went back together w/ out getting cut not even once and w/ no problems. I had a little problem remembering how the throttle plate went in but then I used some common sense to figure it out. See I marked it w/ a permanent marker but when I pulled it out the marking whipped away so it left me clueless. I saw on the edge of the plate where some black carbon had built up and I noticed on the inside top of the throttle body there were 2 holes that came from the EGR. So I just matched up the black edge w/ the top of the throttle body and wholla perfect. Now the shaft doesn't even move a fraction of an inch left and right so that's good news. The old o rings were so bad that they just fell apart when I removed them. It was obvious that they weren't doing anything anymore. The hardest part was getting the spring off the TB, once I released it shot across the room almost hitting my daughter.

Once I get my new BISS and the "O" ring for it I will be able to do the boost leak test again and hopefully all will be well.

Also, those screws in the rod that connect to the throttle plate, I used a drill w/ the best fit phillips head and just pushed like hell and they never even attempted to strip so they came out perfect and I snugged them pretty damn good back in.

[tfoti]

I got a new BISS from Extremepsi and it was nylon. I kept the old metal one in and just replaced the O-ring.

So for your TB, you actually used O-rings? Just wondering since i ordered mine from Kaman direct and they were made by SKF. They were actual oil seals like a cam seal or crank seal, just very very tiny.

Glad to hear you got those screws out without a problem. I used locktite on mine.

[ned032002]

Yeah I just read through the faq again and they say right in there the size of o ring that needs replaced and to clean out old metal holder and replace old o ring w/ new one. Take a look at the vfaq the guy that does the repair shows the pictures along w/ what to do.

[tfoti]

Yeah I read that many times before and during the time I did mine. I'm wondering how long each would last compared to each other. The ones I used are actually metal encased in rubber. I'm thinking the silicone grease will prolong it even longer. Either way is good though.

Congrats on a job well done. How's the boost leak test look?

[ned032002]

I'm waiting on the new BISS screw because mine was destroyed when I went to turn it. The top part of it broke off so I had to drill into the piece left in then sink a screw into it then remove it from the TB. The guy I bought the car from had already replaced it but obviously they don't last long. Is there a dealer that sells a metal one that won't brake as easily?

[tfoti]

jnztuning.com > OEM parts >

MD614948 - BISS
MD614150 - BISS rubber cap
MD608806 - BISS o-ring (#5)

I got mine from extremepsi.com These parts are so cheap I doubt you would want to pay shipping unless you need to order another dealer item. I don't know if there is a mitsu dealer out in Olean or not?

[ned032002]

Good news!! Replacing those o rings fixed the leak in and around the throttle body.

But now I've got another leak. I'm leaking around I think all 4 injectors, 2 of them for sure but possibly all 4. Does this sound normal? I'm doing the boost leak test at 20psi. As far as I can tell this is the very last possible leak. There are no other leaks other than the injectors. I found on Extremepsi the injector o ring kit that includes all the seals necessary, all together for item plus shipping it came to just over $21.

On that site that you posted, I can't access those part numbers and I can't find what I need on there.

Is there a dealer online or person on here that knows of a place to get the OEM BISS? I got the extremepsi one and I don't like it at all. It's nylon I think and it just seems very cheap like it could break off inside or it could get stripped easily. I really want one that is some type of metal so it won't strip as easily and so it won't break either. I've searched online w/ no luck. Thanks guys.

[tfoti]

It works for me. Are you searching by part number? Don't pay any attention to year, make and model. Right underneath just copy and paste, click search and on the next page at the right you'll see a description of the part number and price. Underneath it will say add to cart. I just did it and it works.

[ned032002]

Got it!! Ordered all three items, what is the BISS screw made out of? and what do you think about the injectors?