Originally Posted by TomJames
I have a 2005 34 ft. Alpine with the ISL engine. I have 2 questions. (1) Is there a coolant filter and if so where is it. (2) I believe that the anti-freeze is a regular automotive antifreeze and if it is how do I flush the system and what type of antifreeze should I replace it with? Thanks for any advise. --Tom--
Coolant is actually a complex subject. Unless you bought the coach new you Most likely don't know what you have now or how long it has been in there. The coolant is not standard automotive coolant. It's most likely a heavy duty, low silicate coolant formulated for heavy duty diesels. It must have an additive package called SCA or DCA which is checked with a test strip and replenished annually.
I just finished this job and I refilled with Fleetguard ES Compleat EG which is fully formulated with the proper DCA level. This coolant is available either concentrated or mixed 50/50 with water.
If your current coolant looks good with no cloudy or rusty appearance you should be able to flush with tap water and refill. I followed the following procedure:
1. Warmed engine to running temp so thermostat would be open.
2. Removed pressure cap at surge tank.
3. Open lower radiator petcock.
4. Caught old coolant.
5. Refilled with tap water
6. Warmed to running temp.
7. Repeated dump & refill until color of coolant was nearly gone.
8. During all of the above the heater control should be at full hot.
9. No matter how you do it, there will be a significant residual of water remaining in the system. If you know the approximate volume of coolant in your system that's a good thing.
10. If you know your coolant volume, then add 1/2 of that total of concentrated coolant to the system. Then add distilled water until full.
11. Run until engine reached running temp. Pull a small sample and use a test strip to check DCA level and freeze temp.
You are shooting for a coolant concentration level of approx 50/50 coolant to water. If you get higher it starts impacting heat transfer within the engine.
No question I was lucky. My coolant system design did not cause any air lock while doing this procedure and I ended up not having to add any coolant after my first trip.
There is a product called OAT coolant that does not require annual DCA replenishment. If you use one of those then the process of draining and flushing is much more exacting. It also is much more important to top up with the same product or you can compromise your cavitation protection.
If you are not checking your DCA level at least annually you should start. If your DCA is not maintained at the correct level then cavitation can cause serious engine damage..