BHW Coolant \ Heater Hoses Life Expectancy

DeliveryValve

Veteran Member
Joined
Mar 27, 2007
Location
Western US
TDI
Passat GLS Wagon
Question? What kind of life are you all getting from your coolant/heater hoses?

My 2005 has over 200,000 miles and all the hoses (except elbow hose for the rear flange, 5 years\70,000 miles), are original. They all appear to physically look good.

But given the mileage and age, I am thinking it's time for replacement of the all the hoses.

Part numbers for hoses:
4B0 121 055 J - Lower radiator hose and adapter hose to expansion tank/reservoir (2 hose assembly)
8D0 121 101 AB - Upper radiator hose
8D0 121 107 M – expansion tank to water pipe hose
038 121 086 F - Flange to oil cooler hose and oil cooler to water pipe (2 hose assembly)
038 121 101 - Flange to water pipe
8D0 819 373 N - Heat exchanger to water pipe
038 121 473 B - Rear cylinder head to water pipe vent hose
3b0 121 157 C - EGR Cooler hose to heat exchanger
3b0 121 157 B - EGR Cooler hose to flange

Other part numbers of interest:
038 121 132 D - Rear cylinder head flange
059 919 501 A - Coolant Temperature Sensor
N 903 168 02 Coolant Temperature Sensor Seal
044 121 113 - Thermostat
038 121 119 B - Thermostat neck sealing washer
038 121 121 B - Thermostat adapter/neck

Any opinions if I should go forward, or is there another mileage/age milestone I should wait for?



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1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
It it's not broken, why fix it? All of the coolant system hoses on our '01 Golf are original.
 

DeliveryValve

Veteran Member
Joined
Mar 27, 2007
Location
Western US
TDI
Passat GLS Wagon
I mainly wanted to collect some data points to try to make an informed decision. Perhaps some members or professionals out there had to replace a hose or two. If so, I like to know which one and why a replacement was necessary, along with at what age and mileage.

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Matt-98AHU

Loose Nut Behind the Wheel Vendor
Joined
Apr 23, 2006
Location
Gresham, OR
TDI
2001 Golf TDI, 2005 Passat wagon, 2004 Touareg V10.
Coolant hoses on our cars tend to be made out of a synthetic rubber called EPDM.

EPDM lasts an exceptionally long time (I've seen plenty go well over 20 years). It has great compatibility with glycol based coolants as well as brake fluid.

The downfall? EPDM is NOT compatible with engine oil or diesel fuel. If fuel or oil leaks onto your coolant hoses, they will swell and eventually fail.

So, when it comes to being proactive/preventative with coolant hoses, all you'd really need to do is inspect them for any signs of fuel or oil getting on them and them swelling. On a B5, not unusual for the small hoses on the back of the engine (firewall side) to get oil or fuel on them from the valve cover gasket or tandem pump leaking, causing failure. Those are going to be the most common ones that will need replacing.

Beyond that, if I don't see any sign of swelling/oil/fuel coming into contact with a hose, I leave it alone and have full faith they will last barring the above leaks of incompatible fluids or abrasion.
 

Matt-98AHU

Loose Nut Behind the Wheel Vendor
Joined
Apr 23, 2006
Location
Gresham, OR
TDI
2001 Golf TDI, 2005 Passat wagon, 2004 Touareg V10.
I will also add that many high quality accessory belts also use EPDM rubber and us technicians have had to adjust how we inspect belts because of this change. EPDM doesn't crack like cheaper belts with more conventional rubbers do. There are tools out there now to measure how deep the grooves in the belts are to see if the wear is excessive, thus necessitating replacement, because the belts do NOT crack anymore! Of course if it weren't for the friction driving the accessories, the rubber would last indefinitely once again barring abrasion or coming into contact with incompatible fluids.

Of course with an engine equipped with a timing belt, the accessory belts need to be removed during the process anyway and we just replace the belts then as a matter of course. But EPDM belts seemingly don't have an issue going 100k+ miles without needing replacement because they are just that durable and the rubber is not prone to the traditional degradation/cracking/rotting that we've known previously.

Basically, just trying to say that EPDM anything can last an extremely long time as it does not degrade like more conventional rubbers do.
 

truman

Top Post Dawg
Joined
May 18, 2000
Location
columbia,MO,usa
TDI
'05 Passat Variant, Still miss the 03JW
Thanks
I have often wondered why belts and hoses lasted so long on modern cars.
I remember when 30k was about it
 

DeliveryValve

Veteran Member
Joined
Mar 27, 2007
Location
Western US
TDI
Passat GLS Wagon
Matt, I appreciate you sharing your professional knowledge. Good stuff!

Looks like I will tackle the hoses on the back of the motor and probably another coolant flange replacement. I have an oily mess back there and will be replacing my Tandem pump soon because of a leaking vacuum connection.


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oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Like Matt said, the only time you really need to mess with cooling hoses on these cars is if they get contaminated with oil or fuel.

Which, on the BHW, is typically limited to the small vent hose that wraps around the tandem pump, because oil seepage at the corner of the valve cover over time will distort the end of it where it goes on to the nipple on the head. ALH, BEW, BRM, are all the same way. I also like to carefully inspect the hose to the flange on the back of the head, the small one that goes down to the oil cooler. The big one has never been an issue.
 

DeliveryValve

Veteran Member
Joined
Mar 27, 2007
Location
Western US
TDI
Passat GLS Wagon
Just to update this thread. I had a lot of oil splattered in the back of the engine from the valve cover and tandem pump leaking.

As oilhammer suggested above... The small vent hose 038 121 473 B, mine was scary bloated. The hose to the oil cooler 038 121 086 F and the flange to egr hose 3b0 121 157 B was bloated also.

Since I was touching those hoses, I ended up replacing all the hoses and the flange in the back of the motor. The front hoses all look good and I didn't touch those.


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Andyinchville1

Veteran Member
Joined
Apr 7, 2016
Location
Virginia
TDI
2003 Jetta TDI wagon, 5 sp, 226K miles
Hi

Since this thread helped me i figure i would add a data point.

At about 440k miles my upper radiator hose that joins onto the engine piece where the coolant glow plugs started leaking.

The hose didn't look bad and was not oily or anyting .

After I put everything back together I could still smell antifreeze after a long drive

Long story short, there was a micro leak on the plastic piece that joins the two upper radiator hoses together (has that little third hose coming off of it...).

The leak was at the joint on the underside of the plastic upper hose connector) and it's a very small small leak ... more like a seepage at the Joint underneath the plastic piece ...
I thoroughly inspected the plastic piece because I was very paranoid about that piece and had heard stories of it leaking but I saw nothing...

Anyways it makes me a little paranoid of the other plastic piece coming off of the radiator that hooks onto it with a push in clip but so far that piece seems fine.

For what it's worth I tried to order just that plastic piece from the dealer but they only sell it has an entire hose assembly from the radiator to the engine which includes the plastic coupler to the radiator the two upper radiator hose sections and the plastic coupler piece with the third hose spout .... interestingly it came all pre-built complete with hose clamps.

I was debating about just putting the whole thing on and resting assured that everything on the upper part of the cooling system from the radiator to the engine was new but then again I thought about just taking out that plastic piece that I needed to replace because I was a little leery and how to change the fuse out from the radiator without it causing a big to-do.

How hard is it to remove the clip on piece to the radiator while everything is still together? I think I can get to it by removing the two plastic pieces that make the factory cold air intake from in front of the battery.

Andrew

Ps - I realize that you have a bew and I have an alh engine but I guess the original thread started with hose longevity so I thought I would put my two cents in as far as how long my hose has lasted.... based on what I saw I'm now wondering if my upper hose was really bad or was all of the leakage coming from that plastic piece so maybe we have to be more paranoid about our plastic pieces than actual hoses?
 

DeliveryValve

Veteran Member
Joined
Mar 27, 2007
Location
Western US
TDI
Passat GLS Wagon
I can 't speak to the hose design of the ALH engine because I am not familiar. Perhaps someone in the know will chime in.
 
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