Coolant test?

[cm2785]

Hey guys I have a 2003 w22 with 31,000 miles and the PO seemed to have taken very good care of it. I replaced the overflow tank because of a crack forming and the coolant looked clean and red for the most part so I just poured it into the new one. I’ve changed the engine oil and Allison trans fluid and filters so I have a record on them being done, but I am not sure when the coolant was changed last. Is there a test strip or something to test the life of this particular coolant? Thanks!

[Mark_K5LXP]

So do you re-use your oil filters too? Dump the radiator, put in 3 gallons of new 50-50 and then at least half your system will be fresh. Do this every year and you never have to wonder about your coolant ever again. Costs less than an oil change.

Mark B.
Albuquerque, NM

[wolfe10]

Originally Posted by Mark_K5LXP

So do you re-use your oil filters too? Dump the radiator, put in 3 gallons of new 50-50 and then at least half your system will be fresh. Do this every year and you never have to wonder about your coolant ever again. Costs less than an oil change.

Mark B.
Albuquerque, NM

That works unless you don't know exactly what coolant is in there.


Better not to mix coolants of different chemistries.


So, if you don't know the age/type of coolant, drain, flush with distilled water and go with new coolant.


Agree with you, cost of coolant is nothing compared with the engine, radiator, heater core, water pump, etc.

[cm2785]

Originally Posted by Mark_K5LXP

So do you re-use your oil filters too? Dump the radiator, put in 3 gallons of new 50-50 and then at least half your system will be fresh. Do this every year and you never have to wonder about your coolant ever again. Costs less than an oil change.

Mark B.
Albuquerque, NM

I didn’t know what it had so I didn’t want to add into the expansion tank until I did research, but I was thinning about doing this exact method! Just doing it once a year like this. What is the best way to do this? Just pull the lower hose and drain and fill? I don’t want to make any air pockets, so just want to know the best way to do exactly what you suggested! Thanks!

[cm2785]

Originally Posted by wolfe10

That works unless you don't know exactly what coolant is in there.


Better not to mix coolants of different chemistries.


So, if you don't know the age/type of coolant, drain, flush with distilled water and go with new coolant.


Agree with you, cost of coolant is nothing compared with the engine, radiator, heater core, water pump, etc.

That’s exactly what I was afraid of but my coolant is reddish color. Doesn’t that mean it’s dexcool and I can just add another 50/50 of dexcool like mentioned above? Thanks!

[Mark_K5LXP]

What would be in a mid 2000's 8.1 vortec except dexcool? That's what it came with, and with 31K on the clock it's highly likely this is the factory fill.

Mark B.
Albuquerque, NM

[cm2785]

Originally Posted by Mark_K5LXP

What would be in a mid 2000's 8.1 vortec except dexcool? That's what it came with, and with 31K on the clock it's highly likely this is the factory fill.

Mark B.
Albuquerque, NM

What is the best way to drain the radiator and not get any air pockets? I’m going to do what you suggested once a year.

[JonathonM]

Originally Posted by cm2785

What is the best way to drain the radiator and not get any air pockets? I’m going to do what you suggested once a year.

The red color you see may not be dexcool. It might be rust... Squeeze your lower radiator hose. If it feels crusty, there is a buildup of crud inside.
Several weeks ago I flushed my entire system using the method below. I was amazed at the amount of rust and crud that came out of the cooling system.

IMHO, the most thorough way is to:

1) disconnect the lower radiator hose and drain the block and radiator into a 5gal bucket.
2) remove the thermostat housing and thermostat.
3) put your garden hose in the t-stat housing and flush the block until its clear.
4) put your garden hose in the upper radiator hose and flush the radiator until its clear.
5. reconnect the lower hose. Fill the system with 50/50 through the t-stat housing.
6) reinstall the t-stat and upper hose. Continue filling the system with 50/50.
7) run the engine and get up to operating temp. Top off as necessary.

This may not be the "best" way but it is very thorough (and time consuming). Ive flushed the cooling system on multiple vehicles this way with great results.
There is another method that uses a tbsp of dish soap but it is even more time consuming (and thorough).
Also, IMO, there is no need to change dexcool every year. The stuff lasts ALOT longer than the old green stuff. I change the DC in my pickup every 10ish years or whenever I change a part in the cooling system (whichever comes first).

[cm2785]

Originally Posted by JonathonM

The red color you see may not be dexcool. It might be rust... Squeeze your lower radiator hose. If it feels crusty, there is a buildup of crud inside.
Several weeks ago I flushed my entire system using the method below. I was amazed at the amount of rust and crud that came out of the cooling system.

IMHO, the most thorough way is to:

1) disconnect the lower radiator hose and drain the block and radiator into a 5gal bucket.
2) remove the thermostat housing and thermostat.
3) put your garden hose in the t-stat housing and flush the block until its clear.
4) put your garden hose in the upper radiator hose and flush the radiator until its clear.
5. reconnect the lower hose. Fill the system with 50/50 through the t-stat housing.
6) reinstall the t-stat and upper hose. Continue filling the system with 50/50.
7) run the engine and get up to operating temp. Top off as necessary.

This may not be the "best" way but it is very thorough (and time consuming). Ive flushed the cooling system on multiple vehicles this way with great results.
There is another method that uses a tbsp of dish soap but it is even more time consuming (and thorough).
Also, IMO, there is no need to change dexcool every year. The stuff lasts ALOT longer than the old green stuff. I change the DC in my pickup every 10ish years or whenever I change a part in the cooling system (whichever comes first).

Thanks! It’s definitely red coolant it’s not rust. This is a Southern California rig.. the only thing that stops me from doing it your way entirely is my water here is so bad. I was thinking about doing it as mentioned above getting dexcool and distilled water and draining the radiator and replacing it with 50/50 and then maybe 6 months or so from now doing it again and after a few times it should be flushed pretty good I would think! Unless that sounds wrong to someone?

Also, without knowing what red coolant is in it but guessing it’s the original coolant still at 31,000 miles is there a particular best pick for me to choose for new coolant? Thanks for your help!!

[Mark_K5LXP]

Not sure about anyone else's rigs, but with my Itasca accessing anything on the top/front of the engine is via the doghouse, and not something I would relish doing anything with a garden hose inside.

I have the motoraid feature, so ~50ft of additional hose plus whatever coolant is in the rear heater core and water heater. There's no practical way to drain these things. In my years of fixing and maintaining vehicles it's far simpler to replace a portion of the coolant regularly than to flush and completely replace at extended intervals. It's one less thing to wonder about, even if it's "excessive". I feel the same about engine oil and transmission fluid - there's probably an ideal time to change it but far simpler to do it sooner than later and not watch the calendar, or the odometer.

It's a simple process on my RV. I have a petcock on the driver side of the radiator but past experience with those getting busted in the process, I just remove the lower hose and let it dump into a 5 gallon bucket. I figure it's about half of the total system capacity. Re-attach the hose and refill. Empty and refill the reservoir with fresh. After the first drive cycle the air will purge and then top off the reservoir again when cool. That's about it. After 3-4 changes it's probably "new" enough to let go a few seasons if you wanted, but over the winter I do this along with all the other service I do.

Mark B.
Albuquerque, NM

[cm2785]

Originally Posted by Mark_K5LXP

Not sure about anyone else's rigs, but with my Itasca accessing anything on the top/front of the engine is via the doghouse, and not something I would relish doing anything with a garden hose inside.

I have the motoraid feature, so ~50ft of additional hose plus whatever coolant is in the rear heater core and water heater. There's no practical way to drain these things. In my years of fixing and maintaining vehicles it's far simpler to replace a portion of the coolant regularly than to flush and completely replace at extended intervals. It's one less thing to wonder about, even if it's "excessive". I feel the same about engine oil and transmission fluid - there's probably an ideal time to change it but far simpler to do it sooner than later and not watch the calendar, or the odometer.

It's a simple process on my RV. I have a petcock on the driver side of the radiator but past experience with those getting busted in the process, I just remove the lower hose and let it dump into a 5 gallon bucket. I figure it's about half of the total system capacity. Re-attach the hose and refill. Empty and refill the reservoir with fresh. After the first drive cycle the air will purge and then top off the reservoir again when cool. That's about it. After 3-4 changes it's probably "new" enough to let go a few seasons if you wanted, but over the winter I do this along with all the other service I do.

Mark B.
Albuquerque, NM

Thanks Mark! That’s exactly what I am going to do! Have you ever had any trapped air bubbles? And last what is the best dexcool coolant to go with? Thanks!

[Mark_K5LXP]

Any trapped air works it's way out eventually. The upper radiator hose/radiator inlet is the highest point in my RV, so that's where it would end up at first. After the first couple trips I no longer have to add coolant to the reservoir so it doesn't seem like any air stays trapped for long.

I use zerex dexcool, not so much because I know it's "better" (any one meeting the standard should be as good as another) but because I can find it readily and it's easy to stay consistent with perpetual coolant addition. I buy the undiluted, and dilute myself with distilled water.

Mark B.
Albuquerque, NM

[cm2785]

Originally Posted by Mark_K5LXP

Any trapped air works it's way out eventually. The upper radiator hose/radiator inlet is the highest point in my RV, so that's where it would end up at first. After the first couple trips I no longer have to add coolant to the reservoir so it doesn't seem like any air stays trapped for long.

I use zerex dexcool, not so much because I know it's "better" (any one meeting the standard should be as good as another) but because I can find it readily and it's easy to stay consistent with perpetual coolant addition. I buy the undiluted, and dilute myself with distilled water.

Mark B.
Albuquerque, NM

Awesome thanks so much! Because I don’t know what I have in there now, just that it’s probably the original dexcool it shouldn’t be a problem to add any other brand of dexcool right? Thanks!

[Winemaker2]

A mechanic told me to drill the plate but when I checked my replacement it was already there. He said he drillscany that don't have to prevent air lock and resulting hot spots. The "leakage" by until the Tstat opens is minimal and has no affect on operation.
My boat diesel has a small (1/8" or less) hole in the Tstat plate. Yanmar feels it's beneficial enough to incorporate it into their Tstats.

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