S
Skant
Guest
Yesterday morning, I did the coolant bypass mod on my 1996 LT4. I believe the LT1 and LT4 have the same throttle body, so my experience should be similar to others with the same or close year.
First off, I did search and read all of the information about doing this on these forums. In spite of what I've read, I purchased the bypass kit from MidAmerica Designs. It just didn't seem possible to me that they could be selling a kit which didn't fit at all, and I figured for $20 (plus I was buying other stuff I needed from them anyway), I'd rather have the most official method of doing it.
Just to make it clear to anyone else who wants to do this mod... their kit does _not_ fit. It doesn't even come close to fiitting. It's not like it's a just a poor fit... the piping is nearly twice as large as the hose it needs to fit into. It was clearly meant for a different application.
Okay... here's how I did it.
First, you need to locate the coolant hoses. Not quite as simple as it may seem because there's a lot of hoses running around that area and several large vacuum lines also plugged into the throttle body that don't look much different from coolant lines. I had nightmare visions of getting it wrong and plugging a coolant line into a vacuum line and then starting the car...
One of the coolant lines is on the driver's side of the throttle body. This one is fairly obvious. It connects to a hose which routes under the air intake tube to a three way pipe fitting on the passenger's side of the radiatior.
This hose has a clamp on it. Stuff as much rag as you can under the fitting (to soak up the relatively small amount of coolant that will come out of the line). Use pliers to move the clamp away, and then remove the hose from the fitting.
I found this a little easier said than done. The hose didn't want to budge. I need to use grippers to twist the hose (to break its bond) and then leverage against the throttle body itself to develop enough force to pull the hose off.
More than a few drops of coolant came out of the tube. With the high mounted reservoir, I was wondering if all the coolant in the whole system would come out... I was a little worried that maybe I was expected to just know I needed to release pressure somewhere in the system before doing this. But no... it's not a problem. It did, however, let out enough coolant to soak the first rag, and I needed to replace it with a second.. and then ultimately a third to keep it from soaking enough to drip through.
Check on it every so often. More coolant will dribble out of this fitting as you work with the other side. And it must not be allowed to soak through the rag and drip onto the optispark which is almost immediately below!
The other coolant line is more difficult to locate, access, and remove.
It is located on the passenger side of the throttle body. You will need to remove the passenger side fuel rail cover (the plastic cover that you remove by just popping it out). There are three similar looking hoses connected to that side of the throttle body. The upper two are large vacuum lines. Remove these by hand (it's easy). You will need them out of the way. The lowest of the three is the coolant line. It can be positively identified because it's the only hose with a clamp on it... just like the other side. It is connected to a very short (~3-4 inch) hose that turns 90 degrees to connect to a metal tube which runs along the passenger side valve cover.
You need to remove this short hose completely from both ends. This is not easy. To remove the throttle body side, use pliers to open the clamp and then move it toward the throttle body and onto the fitting. I found that it was impossible to move the clamp along the hose because of its short length and the 90 degree bend... however, the way the base of the fitting is shaped, the clamp will be held away from the hose if the clamp is placed there against the throttle body. Getting the hose off the fitting is not very easy because of how much it has to flex because the fitting on the other side of the bend is right there interfering with its movement.
Once that end was off, I needed to remove the clamp on the other side (that's on the pipe that runs along the valve cover). This was the most difficult task of all. There's a conduit of wires running along side it that needs to be carefully pulled away to provide at least a little clearance. The clamp was upsidedown and nearly impossible to reach. It didn't want to release. It didn't want to move. It didn't want to be rotated.
Ultimately, I was able to use needle nose pliers and a desperate amount of force (you know... the kind that comes as you hiss under your breath 'This bolt is coming off DAMMIT!!!) to finally rotate the clamp enough that I could then access it from the top and pull it down the hose away from the fitting.
Mind you, I thought about using a dremel or some other cutting mechanism to just slice it off. However, a trunk of wires and vacuum lines are right next to it and serve to interfere with accessing it at all. One wrong move and...
Okay... the task was easy from this point. Now that I finally had the &$&#&# little hose off... all that needed to be done was connect the hose that was originally going to the passenger side fitting directly to the metal tube that runs along the valve cover... thusly bypassing the throttlebody.
This fitting is slightly smaller than the one on the other side. However, I read on these forums that others had connected it directly this way. I made sure to tighten the new clamp (I used a screw type clamp) a little extra to make sure it squeezed the hose down around the slightly smaller fitting.
I reduced the length of the hose by some inches since it didn't have as far to reach anymore... and if I had left its whole length, the hose's path would have pushed it against the air intake tube.
I took another car over to Kragen's to pick up some caps to cap off the throttle body fittings. You find them in the 'Help!' stuff. I bought a variety of sizes but ended up using the 5/16" and 3/8".
After all that, I checked under the car and noticed a 2 inch diameter puddle of orange fluid. I'm confused by that because I had rags under the fittings and hoses and could find no evidence of them having dripped through or anything... There was no wetness on the surfaces immediately under any of these fittings. So I don't know what happened there.
I was quite worried I might has messed up somewhat I couldn't figure out and drenched the optispark. But I took it for a spin... and it all seems fine. Kept checking around the fittings... totally dry. The 3/8" cap had popped off somehow during the test drive... so I put a 5/16" cap in its place which was veeery tight to get on... but the new one is not gonna pop off.
So it looks like it worked out.
Anyway... I guess this is pretty long winded for what most of you guys probably find to be a really simple operation. Maybe I'm just a really poor mechanic... I didn't find it incredibly difficult, but I did have some difficulties with stubborn old parts that didn't want to let go...and it took me longer than the time that had been described by others. Mostly because of that upsidedown clamp I couldn't reach.
Hope this detailed description helps someone.
- Skant
First off, I did search and read all of the information about doing this on these forums. In spite of what I've read, I purchased the bypass kit from MidAmerica Designs. It just didn't seem possible to me that they could be selling a kit which didn't fit at all, and I figured for $20 (plus I was buying other stuff I needed from them anyway), I'd rather have the most official method of doing it.
Just to make it clear to anyone else who wants to do this mod... their kit does _not_ fit. It doesn't even come close to fiitting. It's not like it's a just a poor fit... the piping is nearly twice as large as the hose it needs to fit into. It was clearly meant for a different application.
Okay... here's how I did it.
First, you need to locate the coolant hoses. Not quite as simple as it may seem because there's a lot of hoses running around that area and several large vacuum lines also plugged into the throttle body that don't look much different from coolant lines. I had nightmare visions of getting it wrong and plugging a coolant line into a vacuum line and then starting the car...
One of the coolant lines is on the driver's side of the throttle body. This one is fairly obvious. It connects to a hose which routes under the air intake tube to a three way pipe fitting on the passenger's side of the radiatior.
This hose has a clamp on it. Stuff as much rag as you can under the fitting (to soak up the relatively small amount of coolant that will come out of the line). Use pliers to move the clamp away, and then remove the hose from the fitting.
I found this a little easier said than done. The hose didn't want to budge. I need to use grippers to twist the hose (to break its bond) and then leverage against the throttle body itself to develop enough force to pull the hose off.
More than a few drops of coolant came out of the tube. With the high mounted reservoir, I was wondering if all the coolant in the whole system would come out... I was a little worried that maybe I was expected to just know I needed to release pressure somewhere in the system before doing this. But no... it's not a problem. It did, however, let out enough coolant to soak the first rag, and I needed to replace it with a second.. and then ultimately a third to keep it from soaking enough to drip through.
Check on it every so often. More coolant will dribble out of this fitting as you work with the other side. And it must not be allowed to soak through the rag and drip onto the optispark which is almost immediately below!
The other coolant line is more difficult to locate, access, and remove.
It is located on the passenger side of the throttle body. You will need to remove the passenger side fuel rail cover (the plastic cover that you remove by just popping it out). There are three similar looking hoses connected to that side of the throttle body. The upper two are large vacuum lines. Remove these by hand (it's easy). You will need them out of the way. The lowest of the three is the coolant line. It can be positively identified because it's the only hose with a clamp on it... just like the other side. It is connected to a very short (~3-4 inch) hose that turns 90 degrees to connect to a metal tube which runs along the passenger side valve cover.
You need to remove this short hose completely from both ends. This is not easy. To remove the throttle body side, use pliers to open the clamp and then move it toward the throttle body and onto the fitting. I found that it was impossible to move the clamp along the hose because of its short length and the 90 degree bend... however, the way the base of the fitting is shaped, the clamp will be held away from the hose if the clamp is placed there against the throttle body. Getting the hose off the fitting is not very easy because of how much it has to flex because the fitting on the other side of the bend is right there interfering with its movement.
Once that end was off, I needed to remove the clamp on the other side (that's on the pipe that runs along the valve cover). This was the most difficult task of all. There's a conduit of wires running along side it that needs to be carefully pulled away to provide at least a little clearance. The clamp was upsidedown and nearly impossible to reach. It didn't want to release. It didn't want to move. It didn't want to be rotated.
Ultimately, I was able to use needle nose pliers and a desperate amount of force (you know... the kind that comes as you hiss under your breath 'This bolt is coming off DAMMIT!!!) to finally rotate the clamp enough that I could then access it from the top and pull it down the hose away from the fitting.
Mind you, I thought about using a dremel or some other cutting mechanism to just slice it off. However, a trunk of wires and vacuum lines are right next to it and serve to interfere with accessing it at all. One wrong move and...
Okay... the task was easy from this point. Now that I finally had the &$&#&# little hose off... all that needed to be done was connect the hose that was originally going to the passenger side fitting directly to the metal tube that runs along the valve cover... thusly bypassing the throttlebody.
This fitting is slightly smaller than the one on the other side. However, I read on these forums that others had connected it directly this way. I made sure to tighten the new clamp (I used a screw type clamp) a little extra to make sure it squeezed the hose down around the slightly smaller fitting.
I reduced the length of the hose by some inches since it didn't have as far to reach anymore... and if I had left its whole length, the hose's path would have pushed it against the air intake tube.
I took another car over to Kragen's to pick up some caps to cap off the throttle body fittings. You find them in the 'Help!' stuff. I bought a variety of sizes but ended up using the 5/16" and 3/8".
After all that, I checked under the car and noticed a 2 inch diameter puddle of orange fluid. I'm confused by that because I had rags under the fittings and hoses and could find no evidence of them having dripped through or anything... There was no wetness on the surfaces immediately under any of these fittings. So I don't know what happened there.
I was quite worried I might has messed up somewhat I couldn't figure out and drenched the optispark. But I took it for a spin... and it all seems fine. Kept checking around the fittings... totally dry. The 3/8" cap had popped off somehow during the test drive... so I put a 5/16" cap in its place which was veeery tight to get on... but the new one is not gonna pop off.
So it looks like it worked out.
Anyway... I guess this is pretty long winded for what most of you guys probably find to be a really simple operation. Maybe I'm just a really poor mechanic... I didn't find it incredibly difficult, but I did have some difficulties with stubborn old parts that didn't want to let go...and it took me longer than the time that had been described by others. Mostly because of that upsidedown clamp I couldn't reach.
Hope this detailed description helps someone.
- Skant
