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Topic: Coolant pressure tank rust problem (we all may have) (Read 1067 times) previous topic - next topic

Coolant pressure tank rust problem (we all may have)

Two months ago, Bob & Sue alerted us all that they found rust behind their coolant pressure tank.  I wanted to know if we had a rust issue, but was not in the mood to drain and disconnect hoses to remove the tank.  So I started to loosen the four holding bolts with all hoses still connected and tank full of coolant.  Immediately small sheets of rust started to fall down. 

I then removed all four bolts and found a piece of our metal that I could use as a scraper tool in the narrow open space to remove loose rust from wall and tank.

Then we sprayed both surfaces with rust reformer Loctite Extend.  I am aware of other brush on rust reformers, but chose spray Extend which we have used for many years on lots of RV engine area surfaces.

Like others who have gone this route, we now have an air flow behind tank by using spacers with the original bolts.

BTW, our two left bolts are very long and the two right ones are quite short.

I highly recommend everyone checking and protecting as it did not take that much time and a rusted hole will be a big problem.  No reason to wait until coolant is being changed.

I was very surprised to learn about this hidden problem.  Thank you Bob, thank you Sue.

Barry & Cindy

Re: Coolant pressure tank rust problem (we all may have)

Reply #1 –
Great write-up Barry & Cindy,,

I did about the same thing as you guys, except first I pumped the tank dry and then I disconnected all the hoses except the bottom one which allowed me to lay the tank on it's face for better access.  Very minimal surface rust on mine that only required a wire brush and a little Jasco Rust Converter and topcoat.

Thanks Bob & Sue for your original post, "Because rust never sleeps!"
 

Re: Coolant pressure tank rust problem (we all may have)

Reply #2 –
 ^.^d I put this on the top of my to do list.
1994 U280
Build #4451
"If everyone is thinking alike, then somebody isn't thinking"

Re: Coolant pressure tank rust problem (we all may have)

Reply #3 –
Looks like I have another jobs to add to the list.

Thanks,  seriously.
1998 U320 40'
2005 GMC Yukon
MC# 17609

Re: Coolant pressure tank rust problem (we all may have)

Reply #4 –
Thank you Barry for the recognition.
 I do hope that it was the worst "rust " problem on our coach because everything else looks pretty good.  California coach when new and all that. Hope to check bulkheads at MOT this winter.
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR

Re: Coolant pressure tank rust problem (we all may have)

Reply #5 –
A couple of additional things we did:

To get a little more tank movement, we removed the single small overflow/expansion hose to the bottom of the overflow tank.  We removed the rubber hose from the small connector just below the radiator cap.

We painted over the rust reformer with high heat engine black spray paint.  Of course since we choose to not remove the other hoses, we only had about 4-6" of space to do our spraying.

On a related note, we easily add antifreeze to the overflow tank by screwing on a plastic ball valve to a gallon jug.  And with valve closed and the bottom of the jug sticking up into our empty space in rear cap and the valve gadget sticking into the overflow tank, open ball valve and dispense only what is needed.  This type of ball valve is sold in Walmart automotive, etc and will fit several different size containers.  We use a similar gadget for adding oil.

Re: Coolant pressure tank rust problem (we all may have)

Reply #6 –
Just a suggestion, I found that the nipple for the overflow hose to the puke(surge) tank had a very small crack which caused the tank to loose vacuum to the puke tank.... the leak drained into the space behind the tank causing the rust issue.... $65 later at a radiator shop & all was good
'02 40' U320t  4010WTFS Build 6036 1 slide
Motorcade # 17841
SKP 151920
Retired truck driver
 5 million miler
Still have itchy feet for travel

Re: Coolant pressure tank rust problem (we all may have)

Reply #7 –
After the work I did on the tank (wire brush, prime and paint) I am finding a small pin hole leak in the weld on a seam. The overflow tank holds pressure for days but still seeps out of these pinholes ocasionaly.      As I sit here and think about it now,  I'm wondering if the overflow hose is plugged or kinked.  Since the overflow tank has pressure in it, I would think that pressure should push the coolant into the reservoir tank.  May be trying JB weld on it.      It's always something :)
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR

Re: Coolant pressure tank rust problem (we all may have)

Reply #8 –
Quote from: Bob & Sue –
Since the overflow tank has pressure in it, I would think that pressure should push the coolant into the reservoir tank.
It will push coolant into the overflow tank only if the cooling system pressure exceeds the cap's pressure rating and the radiator cap is working properly.
Mark Duckworth
2003 U320 4220
Build 6199, Motorcade 17971

Re: Coolant pressure tank rust problem (we all may have)

Reply #9 –
And then the cap is built to allow coolant sucked back in as things cool down ? 
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR

Re: Coolant pressure tank rust problem (we all may have)

Reply #10 –
Correct.

But, if there is enough air in the radiator (engine side of pressure cap), it will absorb the pressure/release the pressure and the level in the reservoir will not change.

SO, if the level in the reservoir does not change between cold and hot (immediately after engine shut down), wait until it cools and remove the pressure cap and check level.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020