Replacing Metal Intercooler Lines on a GMC Syclone / Typhoon
When GM set out to build the Syclone & Typhoon, the engineering gurus assigned to engine design decided that having crimped metal lines with many bends and twists would be ideal for feeding the water to air intercooler system. Apparently, they never had the enjoyment of working on these trucks either.
These metal lines intertwine through the engine bay (gaining heat along the way), and just get in the way almost every time you work on the engine by obstructing your targeted area that you want to work on. On top of the poor design, it is not uncommon for the black finish to flake off leaving your lines open to rust and corrosion. The now common fix for this hair pulling design flaw is to replace them with rubber heater hose (3/4"), and run them along the back of the engine, or through the passenger fender. This will keep heat out, and provide for quicker flow and ease in removal of the intercooler.
- 15ft of 3/4" heater hose
- Cutting knife for heater hose
- Extra hose clamps
- Distilled water
- Coolant (the green stuff)
- Water Wetter (optional)
Drain the Intercooler
Remove the upper intercooler cap (preventing you from having to drain the overflow bottle as well) and loosen the petcock on IC's heat exchanger (look under the front bumper, passenger side of the little radiator there) with a bucket or container to catch the old coolant. Sometimes this petcock clogs up, blowing in the upper core may clear the plug if it is. Once completely drained, dispose of coolant in the correct manner.
Removing the Upper IC Core
DISCONNECT BATTERY! This one's shockingly important later on.
Begin to remove the turbo to IC hose/pipe that is connected to both the turbo and IC core via a clamp on each end.
Place a clean towel/rag into the turbo outlet to prevent you from dropping nuts/dirt in and causing yourself to start a new project. An alternative is to use masking tape.
On the backside of the IC core (nearest the firewall), loosen the two (2) hoses at the rear of the IC core and pry/wiggle/cut the hose to remove. You will not be using these hoses again, so destroying them is OK.
To finally remove the IC core, you must remove the three (3) 9/16" bolts that hold the core in place. They are located on the underside of the core on 3 separate brackets. Tip - Due to the limited space, it's easy to get these 9/16" bolts loose with a ratchet and extension. Try not to loose them! With the IC core now fully unbolted, set it aside. Leftover coolant may still be in the core, careful not to dump it on yourself!
Removing the Lower Heat Exchanger
Skip this section if you plan to couple the new hose to existing soft lines coming off the lower heat exchanger. If redoing the entire system, continue to Step 2.
There's six (6) bolts, two (2) hoses, and two (2) electrical connectors holding the core on. If you have a lower IC scoop and/or skid plate, begin by removing those items.
On both sides of the heat exchanger core, are two (2) bolts that hold the core to the frame. Remove all four (4) bolts. There are brackets that go from the core to the front bumper support. Remove the single bolts that attach the brackets to the front bumper (if your brackets are over the heat exchanger housing) on both sides. With all bolts removed, the core should be able to move, however it is still attached via the lower hoses.
With the core being able to be moved, rotate around and remove the two (2) hoses (upper driver's side, and at the pump, passenger side). Disconnect the IC pump weather pak connector, and pull the coolant level sensor out.
At this point, you can remove the lower core. The core is sometimes difficult to remove. It will require a little strong arming to get past the bottom lip of the bumper. Take your time, it will come out.
Removal of the Metal IC Lines
You can do this with the hoses still attached (if they are, pull them up so they are loose). Remember that part above about disconnecting the battery? This is where you shock yourself if you disregarded that step. Disconnect the battery now if you havent.
There are 2 methods to removing the lines. If you don't care to save your metal IC lines (they could be worth hundreds one day?) then go with the brute force method of just cutting the metal lines where you see fit for quick and easy removal. For those who care to save their lines and dont mind a bit of extra work, continue to Step 3.
The front (top) line goes under the alternator (there's one 10mm bolt there), across the front of the intake (another mounting bolt, next to the thermostat housing), and turns under the throttle body. Remove the two (2) bolts on this line, loosen and slip the hose clamp near the alternator off the end of the hose. Now, with some careful negotiating this line WILL slip out to the left. Watch the brackets for the line to not damage anything. Once you negotiate the bracket blocking on the left, the lip on the hose, and the brackets themselves, it will pull out by moving left and rotating upward toward you.
The rear (bottom) line goes along the passenger side valve cover around the rear of the intake. There is one bolt holding it to the map/coil/egr solenoid bracket near the valve cover. Removing the map sensor will make this much easier - pull the map out of its bracket, disconnect the vacuum hose carefully, and pull the connecter off. Removing the EGR solenoid lines may help as well. Carefully pull outward on the 2 lines for the egr, grab the plastic hose as close to the rubber coupler as possible, these snap easily. Once the MAP and the EGR lines are out of the way, the IC line should pull out easily.
Bolt up and reconnect the lower ic core, pump, sensor, and hoses. Make sure there's enough hose, but not so much that its bunching up anywhere. Cut any excess and attach the hose ends to the upper IC.
Once the IC appears full, bolt the IC back in and re-attach the turbo/IC hose. Get the IC pump to run (jumper the diagnostic port, or ground the ic pump relay). Watch water level and keep refilling if it drops down. This is where upgraded pumps will show their true colors, the water will move considerably more on a jabsco or shurflo.
Once your satisfied its full, button everything up, make sure there is a little extra in the overflow bottle and go for a drive to heat it up. Check the level again until you notice no difference.
Installing 3/4" hose replacement
This procedure will slightly change depending on how you route your new hose.
Place both ends of the heater hose on the upper IC core and then place the core into position. Route the hoses where you want them. A common routing is to go across the rear firewall and down along the driver's side valve cover into the passage near the front of the engine bay. Others go to the passenger side using pre formed hoses for the tight bends at the rear of the IC (go to a parts store and tell them you need some pre-formed hose, explain the bends/diameter you need and they'll find one you can cut to fit), or carefully routing them over the A/C box, then into the passenger fender and out under the battery tray.
Once you get the IC lines routed to your liking, cut to length. Note: The line from the top of the upper IC core goes to the the top of the heat exchanger. The the line from the bottom of the upper IC goes into the pump.
If youre coupling to the old lines, simply run the short lengths to the old hose with a plastic or brass coupler and install the 4 hose clamps to keep them on.
Bolt up and reconnect the lower ic core, pump, sensor, and hoses. Make sure there's enough hose, but not so much that its bunching up anywhere (cut off any excess), and attach the lines to the upper IC.
Refilling the Intercooler System
To aid in filling, do not bolt the IC in yet. Once the hoses and everything else is re-installed, open the petcock on the lower heat exchanger again. Begin filling the IC with distilled water (add coolant and or water wetter/RMI25). When the fluid begins to pour out the petcock, tighten it all the way. Now hold the upper IC core up and continue to fill the system. This should aid in removing air bubbles.
Once the IC appears full, bolt the ic back in and re-attach the turbo/IC hose. Get the IC pump to run (jumper the diagnostic port, or ground the ic pump relay). Watch water level and keep refilling if it drops down. This is where upgraded pumps will show their true colors, the water will move considerably more on a jabsco or shurflo.
Once your satisfied the system is full, button everything up, make sure there is a little extra coolant/fluid in the overflow bottle. Go for a drive to heat it up, and check the level again until you notice no difference.
With the removal of the metal lines and converting over to 3/4" heater hose, you will find that doing maintenance and modifications becomes much easier. Now by just unbolting the upper IC core, you can lay a towel over the upper intake and have a place to set the IC core without having to remove lines or drain the system due to the heater hose will bend out of the way. This is especially nice for when you set out to change your distributor cap/rotor. The heater hose is also a better insulator against engine bay heat and can also be easily tapped with a temperature gauge if you choose to keep tabs on the coolant temperature (both on the inlet and outlet).