Water in Cooling System

DavidInWilmNC · October 06, 2007, 09:11:06 PM

I'm getting ready to test my cooling system for leaks tomorrow. I've replace all the hose and the thermostats, cleaned and painted the radiators, and painted most of the engine. I've still got to do a couple more things, like drain the lines running to the front, fix the main heater's thermostatic valve, and replace a couple of hoses at the driver's heater. I'd like to check everything for leaks and have the bus movable until then. How long is it 'safe' to have plain water in the cooling system, if at all? I'm planning on draining it and adding antifreeze and water when I'm finished. Would I be better off just using plain water and a couple of gallons of antifreeze (to prevent rust) and then drain it and add the correct amount of antifreeze and distilled water when I'm finished? Thanks for any help or suggestions.

David

JohnEd · October 07, 2007, 12:49:00 AM

David,

Use distilled water to dilute your coolant. None of the "stuff" you find in "normal" drinking water is a good thing for your cooling system.

Why test with water? Coolant is well known to leak where water won't so your "test" isn't much of one. Fill it, fire it up and watch it carefully. Just like a car!

Just what I do with any cooling system.

Good luck,

John

DavidInWilmNC · October 07, 2007, 07:48:46 AM

I was pretty much planning on using plain water, as this will be to also flush out any debris that's gotten in while the system was open. I just wonder how long plain water can be left in before appreciable rusting occurs. I guess I'll just fill it, run it 'til it's hot, see no leaks (hopefully), and then drain it back out. I'm still not sure if I wan to use regular antifreeze or the specified "Detroit Diesel' type. I asked this a while back and got about a 50-50 split on which to use (this is an 8V-71). Thanks.

Daivd

Barn Owl · October 07, 2007, 08:42:50 AM

My bus came from the SW part of the country and the PO ran water (the service manual says it's OK with the correct additives). I don't know if he had any additives in it and additionally it sat for 10 years, so I'm sure if he did they were no good by the time I got it. Rust was a concern for me at first but after inspecting it I found everything to be OK. I wouldn't worry about it.

Laryn

Barn Owl · October 07, 2007, 08:50:32 AM

QuoteI'm still not sure if I wan to use regular antifreeze or the specified "Detroit Diesel' type. I asked this a while back and got about a 50-50 split on which to use (this is an 8V-71)

I had the same problem when I went to service mine. I found out that the 8V-71 is a dry sleeve (thats the determining factor) and you can use the regular car stuff. I added additives that I found out later that I didn't need. Lots and lots of confusion out there on this topic.

HTH,

Laryn

DavidInWilmNC · October 07, 2007, 04:48:48 PM

I got it everything put back together, filled it with water, and found a few leaks. Three were clamps I'd forgotten to tighten - there are so many, it's no surprise I missed a few. One was the oil cooler drain - I'd left it open. Other than that, everything seems good. One thing I'm curious about is that the driver's side radiator got fairly warm, while the passengers' side was mostly cool. I had it running for about 30 minutes or so, on fast idle, with the radiator doors open to help it heat up a bit. It was about 80° outside. The new thermostats are 170°, I believe. I believe the bus was only about 150° or so. Is this something to be concerned with or is it something that has to be tested while the bus is at full operating temp?

On another note, the engine starts so well and smoked for a couple of seconds. It's been sitting since the end of July with no water in it. It took just two pushes of the start button to fire it up... it would have started on the first one, but I didn't hold the start button long enough. It's always nice to know that I've got an easy-starting engine!

David

JohnEd · October 07, 2007, 05:59:29 PM

David,

Great news about the starting. You are soooo right.

I would still use distilled water in the mix. You also hear an awfull lot about overheating problems in this neighborhood. Right?

Good work!

John

Barn Owl · October 07, 2007, 06:26:55 PM

QuoteI would still use distilled water in the mix.

In the final mix I completely agree. I bought my distilled water at Wally world. 68 cents/gal. Don't skimp on something thats very inexpensive and really helps keep the system clean (Said as a general statement for the benefit of others).

Laryn

NJT5047 · October 07, 2007, 08:29:55 PM

Quote from: DavidInWilmNC on October 06, 2007, 09:11:06 PM
I'm getting ready to test my cooling system for leaks tomorrow. I've replace all the hose and the thermostats, cleaned and painted the radiators, and painted most of the engine. I've still got to do a couple more things, like drain the lines running to the front, fix the main heater's thermostatic valve, and replace a couple of hoses at the driver's heater. I'd like to check everything for leaks and have the bus movable until then. How long is it 'safe' to have plain water in the cooling system, if at all? I'm planning on draining it and adding antifreeze and water when I'm finished. Would I be better off just using plain water and a couple of gallons of antifreeze (to prevent rust) and then drain it and add the correct amount of antifreeze and distilled water when I'm finished? Thanks for any help or suggestions.
David

Reckon you better get that bus back on the road fast! Kyle's Largest in the World Non-Rally is coming up next weeken! You gotta be there! DON'T disappoint!
Best, JR

DavidInWilmNC · October 08, 2007, 07:41:23 AM

I'll certainly use distilled water in the final fill. I was mainly wondering about both radiators not being close to the same temp. I was thinking that maybe one had air in it, but the hose on top (to the expansion tank) should take care of that. Am I correct in thinking that on a day that's fairly cool, with little to no load, the thermostats aren't going to open completely? Maybe I should completely block air to the radiators (or temporarily remove the fan belt), wait for it to get up to temp (170-180 or so), and then check both radiators. I guess I'm concerned that one of the new thermostats may be bad. The bypass tube was pretty warm, but not too hot to touch. My new mechanical temp gauge is installed on the side that had the hot radiator; at least the dash gauge is within a couple of degrees of the mechanical one. Both were in the mid 150's. I don't recall there being this difference in temp before, but that doesn't mean that there wasn't. I've also never had any overheating problems, 'cept for the time I blew a hose and ran really low on water in SC on the interstate.

I really wish I could attend the non-rally. I've got so many things apart at the moment that I'd be hard pressed to even get things together enough to get it out on the road, much less actually go anywhere! I'm gonna hate mising it. Hopefully, we'll get something going for the place near Beulaville that Darrell's posted about. Thanks guys.

David

NJT5047 · October 08, 2007, 07:37:49 PM

David, the LH radiator will run hotter than the right side. This is common on MC9s. Not sure why. Could have something to do with the water pump located on the LH side. The RH rad has a lot of friction loss. The only way to get the engine up to operating temp is to get it on the road. It won't reach operating temp sitting and idling. That's one reason running DD 2 cycles at idle to "limber them up" is not the best idea. It makes them slobber too. No one wants a slobbering engine!

Don't worry about a temp differential between the rads unless one of banks is above 200 degrees. Then you got a problem. You may want to check the radiators with your IR gun and see if water is flowing thru the whole core...this will be noted by cool spots relative to the engine temp.
Did you bleed the crossover? You may have covered this? I'll read back thru the threads.
If not the crossover between the thermo housings has a bleeder valve which should purge the air trapped.
We'll miss ya at the Rally!
JR

DavidInWilmNC · October 09, 2007, 12:10:37 PM

Thanks for the info, JR. I guess I never compared the temps of the radiators. I filled the system with the crossover bleeder open. When it started squirting water out, I closed it. Once the filler overflowed, I cranked the engine and was able to add a bit more (maybe a quart or two). The crossover got hot as it ran, so I imagine that it was bled pretty well. I'll have to check it again, but this was a 'test fill' with plane hose water. I'll fill the entire system with distilled water and antifreeze once I get the main heater control valve working properly. I sure hope you guys have a good time at the (non)-rally!

David