How to remove the rear heater in your skoolie

So you’ve got a bus, and you’ve got the seats out – awesome! Now how do you get rid of the rear heater in the bus?

This is an easy DIY that will get you more familiar with your skoolie engine, and make a little extra room while you’re at it. I think it is a good idea to drain and refill your coolant completely for this process. This not only gives you a clean working environment when you remove your heaters and old hoses but also gives you a chance to ensure your bus has brand-new coolant AND you will know exactly how much you need if you ever require a flush in the future – bonus!

Note: An alternative to removing the heater entirely is to move the rear heater if you want more onboard heat while driving. For us, the front driver-side heater and defrost were plenty to heat the whole bus on long drives in the cold, we definitely didn’t need the rear heater in our 26-foot Bluebird.

Tools you’ll need:

Chemical Goggles – you want splash-proof goggles here, trust me and my coolant-covered face
Rubber gloves
Optional – Face Shield
Socket-wrench for hose clamps
Three 5gal Buckets – depending on the size of your bus, be prepared for 10+ gal of coolant to come out!
Large Oil Pan
Utility Knife for cutting hoses
Mechanic’s (Blue) Paper Towels

WARNING! Coolant / Antifreeze is poisonous! Most coolant has Ethylene glycol added as an antifreeze agent. Ethylene glycol tastes sweet to humans and animals but is highly toxic. Please, do not leave any coolant on the ground, or exposed in buckets, as wild animals are known to be attracted to the taste and will die. Take care of our animal neighbors!

While the coolant is toxic, don’t worry if you get it on yourself – you can wash it off and you’ll be just fine. Just don’t get any in your eyes or mouth.

Removing the rear heater and looping the hoses

Now that you’ve got your tools, and you know that antifreeze is poisonous to animals, you’re ready to get started! This is an easy, but messy job – let’s get after it.

Draining the coolant

Step 1: Make a diagram of your hoses so you know the flow of coolant and where to loop the hose when you remove your heater. See my diagram below for our 1995 International 3800 DT466:

Step 2: Draining the engine / radiator coolant: This may sound daunting, but it is a piece of cake and will assure you that your engine has brand-new coolant in it before you hit the road – nice!

Start by locating the valves in your coolant system. This will be vital information down the road when you need to turn your heater on or off for the season, or if you ever need to work on the coolant system.
Make sure all of the valves are OPEN for this procedure, we want to drain the coolant out of the entire system.
Next, locate your radiator drain valve – this is at the bottom of your radiator and will be a bolt or butterfly-nut, or possibly even a small valve.
Place your large oil pan directly underneath this drain valve, then put a 5gal bucket inside of that. This ensures that any splashing or over-pour out of the 5gal bucket will be caught by the oil pan instead of getting all over the ground.
Open the TOP of the radiator by removing the radiator cap. Place the cap somewhere safe where you will not lose it 😉 Removing the cap allows the coolant to flow freely out of the system once you open the drain valve
Once the bucket and pan are in place and your radiator cap is removed, slowly open the drain valve at the bottom of the radiator. Coolant will start to flow and you may need to adjust the bucket to catch it all.

Tip: Make note of the color of the coolant as it drains out; is it yellow, green, orange, or red? This will determine what kind of coolant needs to go back in.

Keep an eye on the coolant as it drains – it is very likely that you will need to swap to a new bucket halfway through so don’t let your bucket get too full, and be ready to close the drain valve to swap buckets.

cutting and removing the rear-heater, and/or entrance door heater hoses

Step 3: Now that your engine-side coolant is drained. You’re ready to cut some hoses and drain some more coolant!

Head to the back of the bus where you’re removing the heater. We were lucky with our bus and all of the coolant hoses were located under the bus, making for easy cut-and-drain access. If your hoses are on the inside this step may be a little messier, but still a quick and easy process with an easy cleanup – no worries!
Place your oil pan and fresh 5gal bucket underneath the hoses just before they meet the heater. You’re going to cut the hoses just before the heater and any coolant left in the hoses will start to pour out so be sure you have eye protection on, and your 5gal bucket is ready to catch the drainage.
Once you’re in position with your bucket and your eye protection, cut those hoses! Satisfying, or stressful?
Repeat these steps for your passenger door heater if you’re taking this out as well.

Step 4) Once you feel like all of the coolant is done draining from the heater and the coolant hoses, you’re ready to start removing all of that old hose. This will A) help make some room underneath, or inside your bus, B) remove a little bit of weight (not noticeable), and C) give you TONS of old coolant hose to re-use, or recycle – nice!

This process is pretty straightforward – just follow the hose back to the engine, cutting zip ties or loosening cable clamps as you go to free the hose. Our hoses had old, brittle, nasty black insulation foam around them that I had to break off while removing the hoses. This was one of the dirtiest jobs in the entire conversion – but worth it in the end to get 40+ feet of usable silicone coolant hose!
Once you get back to the engine with the removed hose, follow it to wherever it connects to the driver heater and the engine – this will be your loop point (see diagram above).
Once this old hose is out, the coolant will flow directly from the engine to the driver heater and back.

looping the coolant hoses

Step 5) Your driver heater and passenger door heater are likely already connected to the engine via the return hose, so all you need to do is cut a new length of hose to fit from the engine to the driver heater, replacing the hose from the heater to the passenger door heater.

Note: please feel free to email me if you have any questions – I’m happy to troubleshoot with you. Pictures are vital to helping you out remotely though, so take as many as you can 🙂

Step 6) You can re-use the hose clamps, or install new ones – mine were in great shape so I just reused them. Clamp down your newly connected hoses and then take a look at your original diagram. How does everything look? Trace the new hose from the engine to the driver heater – does it look like a clean bypass of the old hoses and heater? Now trace the hose from the driver heater back to the engine – still in the same position?

If everything is connected securely, you should be good to go. Basically, the flow of coolant just needs a clean path from the engine, through whatever heating device you’ve installed in the loop (in this case the driver heater), back to the engine.

Refilling the coolant

Step 7) Now that everything is connected and you’re feeling good about the new setup, climb back under the bus and tighten that radiator drain valve. It’s time to fill your baby back up with fresh coolant!

Step 8) It took 7.5gal of coolant to fill our bus with yellow 50/50 pre-diluted antifreeze/coolant. Do some quick research on your engine to see what coolant type is recommended, or refer to the color of the coolant that you drained out of the bus.

Using a funnel, carefully pour the coolant back into the radiator through the open radiator cap. Pour slowly, as the coolant needs time to trickle through the system. Keep an eye on your coolant reservoir as you fill the radiator – I could see my reservoir filling up as I poured coolant into the radiator.
Once the radiator is full, replace the cap and go around to your coolant reservoir – how does it look? Top it off if hasn’t reached the “full” line yet.

Removing the driver and rear heaters

Now that your coolant has been refilled, you’re ready to start the bus and let that heater run for a few minutes to ensure the coolant levels are sufficient. This process will get rid of any air in the system and give you an accurate coolant-level reading in your coolant reservoir. Let the engine get up to temperature, and ensure that hot air is blowing through your heater (all coolant valves should be open).

Now that your coolant system is refilled and ready for the road, you still have to get that heater out of the back of the bus! This is pretty easy now that it is detached from the coolant sytem, and most of the coolant has been drained. Removing the heater should be pretty straightforward at this point, simply remove all screws or bolts holding the heater in-place and yank that sucker out of there! Careful, there may be some coolant left in the heater.

How to remove the rear heater in your skoolie