A Sunday project – replace the heater core in the Jimmy. I didn’t know what to expect, really, I knew it would take more time than the 73 Jeep Commando which had five screws and two hose clamps. I had to remove the dash to get to it and alloted six hours for the deed. Two hours and forty minutes later I had it back better than before and would have been done sooner but I cleaned everything during re-assembly. The lowest mechanic’s price was around $500 so I saved some coins and patted myself on the back.
12262007 – News flash/edit/update. The 3rd party core I bought was thinner than the original and there is a bit of air which bypasses the core so I’ll be taking the dash apart again to install new gasket material around the core. I thought it wouldn’t make much difference in Louisiana but Xmas in OKC at 15-40 degrees with snow and ice requires the gasket mod. I will take a full set of step-by-step pics of the process and post them on a sheet with a link on the first page. It will basically be a heater core replacement. Also, I had to devise a mandrel to bend the input an output tubes to fit properly (without kinking them) – if you do not wish to include field mods and want more efficient heat transfer (more core surface area) pay the extra $50 and get a GM part. Online the parts were around $110 for GM and $49 for China. Stay tuned – I’ll probably do it 12/29-30. Thanks for looking. Mars out.
20090101 New Heater Core – Here’s an update on the Jimmy. Mileage is now 215,000 and fuel was 24.76 mpg LA to OK @ 65-67 mph. For those who have read entries related to this machine you’ll know I replaced the heater core and it started leaking last summer so I bypassed it and put the repair on the back burner. With trips home to Oklahoma from southern Louisiana almost bi-weekly I needed to replace the core again and took a few hours to do this back in September, 2008. Here are a few comments and images to go with the task. Anyone can do this. This looks and sounds complex but it can be done with a little time and patience. If you are not motivated by the cold to take up the project then maybe the fact the lowest quote from a garage (on the first core) was around $450. A heater core costs $40-100 at O’Reillys. If you have a helper it will go quicker but plan on 3-4 hours for a first timer.
These notes supplement the GMC, Haynes, Chilton, et al manual instructions and are not inclusive of the project. Search the Blazer and Jimmy BB threads and you’ll have plenty of info. A set of 3/8 and 1/4 metric and SAE sockets with a couple extensions, 3/32 nut, torx and screw drivers will do it. Also, if there is a gap due to the core being thinner you may want to have foam strips or a tube of RTV ready.
There are a couple of things which make these jobs go smoother. Work in a clean space. I take an old piece of cardboard and use it like a storyboard for storing the screws, nuts and bolts. Puncture the cardboard and make a note where the screw goes. A roll of duct or masking tape help secure the nuts. You can use several and store them in sequence and draw little schematics or instructions such as “the rubber washer goes behind the plate before mounting on the bracket”. A large piece of carpet or mat make the contortions needed removing the under dash trim and screws a little more bearable while kneeling outside of the vehicle. Bright lighting will make it easier, too.
Before disconnecting the battery its easier to work and remove the dash if the front seats and console shifter are moved back as far as they can be moved. Do this first. Block wheels or set parking brake. Put the key in the ignition, turn to “run” position but do not start. This releases the shifter. Move it to 1 position. Now you can disconnect the battery.
To complete any project I give you the authority and permission to create purpose-built tools to make the job go easier. Here’s a torx driver I cut the handle off so it would fit under the slope of the windshield to remove the speaker grilles. There is a dash screw under each speaker grille and two under the defrost vent grille.
Some trim pieces snap in place and some have screws. Look closely and pry carefully. On older vehicles the plastic becomes brittle especially if the piece is exposed to sunlight (that‘s basically all of the interior plastic). Remove the trim under the dash – all plastic panels. There is a nut over the gas pedal which will need a deep socket.
Leave the emergency brake handle in the trim. You can remove the cable nib from the hook on the release mechanism.
It is not necessary to remove the radio from the dash but you will need to disconnect all of the light switch connectors. All of my connectors were different so there was no need to mark them – they only fit back together one way.
Have a towel or cloth ready to put on top of the steering wheel when you lift out the dash. The wheel will make a rubber smudge on the speedo glass if you don’t. How do I know this?
The original GMC core is thicker than the two aftermarket parts I worked with. When you replace with the thinner core you may want to close the gaps on either side with a foam strip, rtv, or gasket material. The gap is about ¼ of an inch. You’ll see… Go buy it now if you don’t have any.
The cores I bought both required field mod bending of the in/out tubes to fit through the holes in the fire wall. Bend carefully (I used two pair of large Channel locks on the second core) so you don’t weaken the crimped retainer where the tube meets the core. It will leak.
Put it back together and turn on the heater.
end heater core info
——- Jewelry bench stuff
For those interested in jewelry fabrication I’m starting posts following my view of/and the process of creating wax patterns for casting in spite of the simple fact there exists a stupid amount of information in books and the internet relating to this process. I don’t have all of my tools handy (they are in another state) and want to start now so I went to Lowe’s and bought a couple of file sets. The tools I’m assembling will include bamboo and wood dowels and square shapes for carving in addition to an x-acto knife set. You may also use the set sold for block print carving at the art supply store.
Carving projects and processes are easier than they look. The first step is to start where you are. Simple tools on the wax bench will get it done. Pieces of wood, sand paper, nails, pins, anything with a point which can be sharpened and is small will aid your wax carving. You do not need swiss files or the surplus dental picks at $10 per piece (they are handy, though). Good glasses, good lighting and a steady hand are probably the minimum. Design and skill are either there or not. Wax is forgiving in that mistakes can be corrected by adding wax. Basic choice is to remove wax (carve) or build-up (form with drips or wax welding pieces together). We’ll look at the tool side first.
(i’m posting this before the images of files so check back)
Picked up wax tools and bench over Xmas will start pages on wax carving. M
Mars out.
