# 3126B CAT diesel coolant replacement procedure?



## dhshipley

We have a 2000 Airstream 350XC built on a freightliner chassis with a 3126B Caterpillar engine. We bought it this past summer and it's the first diesel I have ever owned. I discovered that it had pure water in the generator and the engine and it was supposed to get downin the 20s that night so I drained them both. The generator was easy. I just followed the manual, it was clear. The chassis manual was not so clear about the coolant replacement. It mentions an "engine venting petcock" and says that air must be vented from the engine to prevent damage. I cannot find this petcock on the engine. The only info I can find on the internet says to fill the coolant system and run the engine. But I'm not sure they are talking about the same engine! Anyone got any knowledge of this procedure?


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## C Nash

Re: 3126B CAT diesel coolant replacement procedure?

Welcome to the forum David and Peggy.  Are you just draining and replacing with antifreeze or just draing the water to empty.  If you are just draining you will have to find the pepcock for the engine block or it will still have water in the block which can freeze.  If you are just installing antifreeze you should not have to drain the block.  Just install the recomended amount in the radiator and run the enging until reaching operating temp.  Not familiar with the diesel system as most of my experience is with gas but Rod will be on later and can better advise so keep check.


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## Triple E

Re: 3126B CAT diesel coolant replacement procedure?

Hello and Welcome to the site.  Be sure you use antifreeze for a diesel engine.  Not for gas.  Cat will have the correct antifreeze and it is not over priced.  I just had my 3126 drained and refilled.  All that I know is after they filled the system they left the cap off of the radiator, ran the engine at 1200 rpm for about 45 min's. then at 1500 rpm for about 5 min's.  Also make sure you run your air conditioner to circulate the antifreeze thru the whole system.  Is your hot water tank heat by your engine coolant?  If so make sure all valves to your hot water tank is open. I do not recall for sure but seems I used 5 gallons of antifreeze.   Now you know what I know.  Good luck.   :approve: 


 :8ball:


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## Triple E

Re: 3126B CAT diesel coolant replacement procedure?

I just checked my Invoice.  I used 6 gallons of antifreeze at the cost of $12.56 per gallon.  I also have a good write up on the HUEI pump.  If you would like a copy of this, email me with your email address and I will send it to you.


 :8ball:


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## Guest

Re: 3126B CAT diesel coolant replacement procedure?

Well not to sure about the "NEW" cat motors ,, but most all diesel motors need to have the air bleed open ,, due to the sleeves and such ,, and most ,, have radiators about level with the engine ,, so that means air can not escape ,,but if u are just doing a drain and refill ,, i IMO would not worry about the bleed valve ,, since u already have fluid in the block ,, just use more antifreeze ,, than water ,, and as others have said use Diesel only ,, the regular stuff will pit the cylinder sleeves ,, hope this helps ,, but feel free to come back and ask more  :approve:  :approve:


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## dhshipley

Re: 3126B CAT diesel coolant replacement procedure?

TRIPLE E:
I PMd my email address to you. I'm going to leave it here in case you don't get it that way. I'm new on this and I'm not sure of what to use!  My email is dhshipley@cinci.rr.com


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## Triple E

Re: 3126B CAT diesel coolant replacement procedure?

I sent it twice.  I think I messed up the first time.  Anyway it is on it way.  Enjoy.    



 :8ball:


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## TexasClodhopper

Re: 3126B CAT diesel coolant replacement procedure?

For any of you newcomers to the forum:

Never put your email address out in the open forum (or any other private information) ... it will stay there forever for spammers to harvest at their leisure.

The personal message (PM) part of the forum works very well and posts there are not available to spammers.


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