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Topic: Engine Coolant Tank Fill Level (Read 1389 times) previous topic - next topic

Engine Coolant Tank Fill Level

1998 U-320 M11 Celect Plus 450 HP engine

I searched the forums but only found one response, and want to double check.

Coolant in the metal engine coolant tank is about half full (well above the sight glass but a few inches below the filler neck).  Overflow tank is above the cold line.  New radiator and on a six day drive the engine coolant temp was fine. No leaks in system when parked.

Should coolant be added to the coolant tank, and to what level?

About to start a long drive back home and am checking fluids before departure.

Thanks,
Chris

Re: Engine Coolant Tank Fill Level

Reply #1 –
Chris,

YES.
If you have an overflow tank, it should be up to the cold level when cold, hot level when hot, WITH THE RADIATOR/METAL TANK (basically anything on the engine-side of the pressure cap) full.

After servicing the cooling system, it is normal for it to take a couple of "top offs" to get all the air out of the system.
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

Re: Engine Coolant Tank Fill Level

Reply #2 –
Make sure your overflow tank is set up to return the coolant to the metal tank when the engine cools off after running.  We had a recent discussion with another member who was losing coolant because he was missing a simple plastic tube in his overflow tank.

Overheating Help: FT GV with Chevy 454 on P-30 Chassis '87
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Engine Coolant Tank Fill Level

Reply #3 –
Thank you both for your replies.

I will top off the metal coolant tank.

The plastic overflow tank has two hoses:
    • one on the bottom of the plastic tank that returns to the filler neck on the metal tank
    • one on the top of the plastic tank that runs down the outside of the plastic tank and is open on the end to allow coolant to pour out if the plastic bottle gets too full

Re: Engine Coolant Tank Fill Level

Reply #4 –
I just had mine flushed and filled. Day one, the engine rand about 9 degrees warm. When stopping for the day, topped up the plastic reservoir to the "HOT" level. In the morning, engine sucked in quite a bit as it cooled. Day two, rand about 3 degrees warm. Repeat process. Day three, ran at tHe proper temp and no coolant in the reservoir was required. Seems you have to work on "burping" these systems.
Alan & Gerri Ortiz
1996 U295 36 ft.
"Rocinante"
Hartwell, Georgia
1999 Subaru Forester
Build No. 4957 Motorcader 17399

Re: Engine Coolant Tank Fill Level

Reply #5 –
When we say to fill the steel radiator tank, we mean really full-right up to the level of the overflow tank tube.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Engine Coolant Tank Fill Level

Reply #6 –
Yup, My nipple @ the metal tank  for the hose to the overflow tank had a tiny crack @ the tank neck/cap. This caused the system to not create a vacuum & suck the coolant back into the system when the engine cooled..
'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: Engine Coolant Tank Fill Level

Reply #7 –
Quote from: Chuck & Jeannie –
Make sure your overflow tank is set up to return the coolant to the metal tank when the engine cools off after running.  We had a recent discussion with another member who was losing coolant because he was missing a simple plastic tube in his overflow tank.

Overheating Help: FT GV with Chevy 454 on P-30 Chassis '87
Is there supposed to be a tube inside the overflow tank?  I've been losing coolant and assumed it was because I had recently replaced my radiator and it was still purging the air.  I went back to check and just now found that my over flow tank cap is split.  Does anyone know where I can get a replacement?
2000 U320 mid entry  #5688
2006 Jeep Liberty


USMCR retired
SDFD retired
FEMA US&R TF8

Re: Engine Coolant Tank Fill Level

Reply #8 –
It returns out the bottom of the overflow tank no tube needed.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Engine Coolant Tank Fill Level

Reply #9 –
Two different types of overflow tanks.  Either one accomplishes the same purpose: returns the captured liquid to the radiator.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Engine Coolant Tank Fill Level

Reply #10 –
Quote
Does anyone know where I can get a replacement?

I bought an exact replacement once from Foretravel. Pricey at around 60 bucks. Might be able to find it cheaper elsewhere.
jor
93 225
95 300
97 270
99 320

Re: Engine Coolant Tank Fill Level

Reply #11 –
Quote from: Sven and Kristi –
Is there supposed to be a tube inside the overflow tank?  I've been losing coolant and assumed it was because I had recently replaced my radiator and it was still purging the air.  I went back to check and just now found that my over flow tank cap is split.  Does anyone know where I can get a replacement?
If you are just after the cap, there have been posts about them. Here is one of them. It is an old post but has the part number

Radiator Overflow cap found
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Engine Coolant Tank Fill Level

Reply #12 –
Quote from: Sven and Kristi –
Does anyone know where I can get a replacement?
Howdy Sven,  I did like Beerslayer_24: Plastic overflo tank cap
and bought a spare from Roger: Expansion Tank Replacement Cap - Vented
Good Luck, Dave A
Dave and Nancy Abel
'00 U320 36' WTFE  Build #5669
'10 Jeep Wrangler Unlimited Rubicon
Livingston, TX  SKP's Fulltiming
 

Re: Engine Coolant Tank Fill Level

Reply #13 –
A quick follow up.

It turns out we did have a couple leaks in components on the metal coolant tank that were revealed after topping off the tank, firing up the engine, and inspecting.

1)  The cap on the metal coolant tank was the wrong type and leaked - one drip every five seconds.  It was a 10# cap without a second gasket at the top.  The correct cap is a 15# cap with a second gasket.  Replaced the cap and the drips stopped.  Per Foretravel parts dept, the correct coolant tank cap is NAPA part #:  703-1427

2)  the rubber overflow tube (leading from the nipple on the filler neck to the plastic over flow bottle) had a split in it at the barbed nipple on the filler neck of the metal tank.  The bad section was cut off, a constant tension clamp was added to the tube, and the plastic hose supports screwed into the back wall were redone so the hose didn't bend at the nipple and to provide more slack.

Chris