How To: D24T Heater Hose Replacement, On a Budget

[v8volvo]

The below is a method for replacing heater hoses on 700 or 900 series D24 or D24T. Most of this may work on a 200 series diesel as well with some small changes. New heater hoses are expensive or no longer available from Volvo, but can be fashioned at low cost using these readily available parts.

For the hose from the back of the cylinder head to the firewall, a heater hose with part number 171 121 611 E from a VW Rabbit diesel has the required 7/8"-to-5/8" reduction with a 90-degree bend just after the larger attachment point, reducing to 5/8" after the bend. To complete the rest of that hose, use two right-angle 5/8" hoses and a simple 5/8" OD brass union. Use the union to adapt from the Rabbit heater hose to the first 90-degree elbow, then use the heater control valve in its proper position and orientation to join to the other 90-degree piece (some trimming required of all pieces to get all the turns and sections in the right place).

For the second hose assembly, the one that runs from the firewall, under the IP, along the side of the block and ends at the thermostat housing, you need a short section of 7/8" hose (6-12 inches), a 5/8" to 7/8" brass reducer, and a good-sized length from a roll of standard 5/8" heater hose (at least 3 feet). Use a piece of 7/8" hose from the outlet to the tee piece (with small-diameter connection for return hose from cold start thermostat), then another short piece from the tee to your adapter. I located the 7/8"-to-5/8" adapter just before the fuel filter head so that the hose clamps would remain accessible. From there, the 5/8" hose is flexible enough to be installed in a corkscrew shape skirting the injection pump and leading up to the firewall with no small-radius bends, in a shape similar to the routing of the original Volvo molded hose. You may have to use wire ties to secure this section of hose to the brake lines next to the brake booster, to keep the heater hose from fouling the end of the throttle lever and preventing the engine from returning to idle.

Works well and looks inconspicuous enough, with most connections hidden, that you wouldn't notice it didn't have OE parts on it unless you were looking pretty close. The cost for the complete recipe can be as low as $20. The Rabbit heater hose is easy to find for $10 or less. Everything else is basic auto parts store or hardware store stock. Worth the price and effort to avoid a burst hose if you have hose damage from a leaky IP.

[RedArrow]

vw rabbit `84. Part # 171 121 611 E.
I love it! Thank you so much v8volvo!

http://www.rapidparts.com/searchitem.epc
Picture taken *after* my cleanup

Yes I know, the glow plug sensor wire isn`t connected; probably I bumped into it while trying to remove all that oily crap. I noticed it when started car. The orange coloured indicator `glow-plug dash-light` did stay on for too long, like 2sec *after start-up (cold motor). System thought it was VERY cold outside... I pushed it back on, now glow-light disappears in just a few seconds.
BTW, I`ll clean that area & seal that wire.

[RedArrow]

I had some time for a joke and to experiment... I didnt even take myself serious when I stopped today at Aut*zone to ask IF I CAN ORDER a coolant hose for a 1984 (`WHAT????...a 19.. what?1984?`), so a 1984 VW RABBIT (`WHAAT?)Is that a VW?`)
...and so on. Honestly, I gave up *before* even asking for an ancient auto part. Especially there.
Line behind me looong, but guy grabs it off the shelf,brings it in 3minutes. I said: ``WHAAT? You have it? I can`t believe it!!``

Friend was with me with a 2005 Passat but he could not buy rear pads, neither a set of coolant hose. He cursed me out a few times including my he says `30y old car` then we drove away.
So I have the hose for $7 and will redo the one at the back of the engine.
It has the right size and curve, just as v8 described it. Many thanks.

[ngoma]

Helpful Tip:

When replacing the heater hoses at the rear of the engine, replace the o-rings for the nipple flanges that the hoses connect to. One at the rear of the block, the other at the rear of the cylinder head. They deteriorate with time, especially if the engine has seen overheat conditions and/or oil into the coolant.

They are standard size metric o-rings. I replaced mine from a common nitrile o-ring assortment set .

[RedArrow]

Sounds like a good idea to replace those.
I cant remember seeing them though. So I guess I need toget the flange off to find them?
Does someone have an actual picture to illustrate?

[ngoma]

When you remove the flange you will see there is a recess cut out of the edge of the hole in the engine where the o-ring seats. Very similar to the relief the thermostat o-ring sits in, but smaller.

The o-ring for the heater coolant flange in the rear of the head measures 22 x 3mm. I didn't measure the one for the rear of the block. That one may be larger because the hose that connects to that flange is 7/8" as opposed to 5/8" for the one on the head.

Sorry, no good access for taking photos because they are right up against the firewall.

Maybe I will experiment with viton next time because I recently had to replace a somewhat fresh (1 year old?) leaking nitrile one, no overheats in that time period.

Did your car suffer overheat condition or oil-in-coolant condition?

If it wasn't leaking, and if I wasn't replacing the heater hoses I wouldn't replace the o-rings just to replace them. If it goes, it won't be a catastrophic huge leak (you will see coolant slowly dripping off the bellhousing and it will stay that way for a long time).

Difficult access, hard to turn a wrench in there, hard to get your hand in there to seat the o-ring properly. Better to expend the energy inspecting (and replacing as necessary) the coolant hoses under the IP which are subject to fuel leaking from the IP or injector spill lines. If those let go, that definitely has potential to cause a catastrophic overheat condition. Sudden loss of coolant.

[RedArrow]

Thanks for taking the time to describe!

I looked at the area at the rear of the engine, I used a small telescopic mirror and I saw the flanges you were pointing out.
I don't recall seeing these when last year I built new lines to replace all the cooling system hoses on/for two engines (maybe because they were nonturbo motors that dont have those(?), i'm not sure). Anyway, as you suggest, I'll simply not disturb those o-rings unless they start leaking. Though it is pretty hard to successfully monitor the area for faults, and it is not the cleanest parts of the engine either, I'll still keep watching them.

I should have replaced that rear hose long ago bc engine oil does get on it frequently (valve cover is suspect) and bc it has been long years since the car was built. It will be a good occassion maybe when the timing belt(s) get replaced.
I would probably get the upper radiator hose replaced too, because that's the one exposed to probably the most amount of heat, dust, oil and/or fuel mist.
The one under my injection pump is exposed to most of the worst: dirt, oil and fuel...but on my car that hose is so hard and thick that I'll probably leave it alone (maybe some special heavy duty hose)
Answering your question about overheating in the past; luckily that hadn't happened. And there is/was no oil in water, so the o-rings in the rear are probably in good condition.
The other coolant hoses look completely fine but I was wondering whether or not it is suggested to get them replaced anyway...because, as you said, " a sudden loss of coolant is a catastrophic event" ....but again, they are probably only 7yrs old and have about 40k (gentle) miles at the most. Monitoring coolant levels would be the bestinsurance for all of us. It is absolutely crazy that these engines never had an alerting system for the driver to immediately signal an unfortunate&deadly coolant fluid level drop.

A radiator flush (and hopefully the flush of the entire engine) will be performed just in case when the waterpump gets replaced at the tb service. But im sure that for this particular car, it isnt necessary actually. And im not sure how i could get ALL OF THE LEFTOVERS OF THE FLUSHING LIQUID BACK OUT.
That tb service is on mind mind now so badly...
It's been 7yrs and about 40k miles since the full refurbishing of this engine took place.

Luckily I have the factory tools. And the literature. But i have tons of qs...maybe i'll open a separate thread for them.
Because I have tb picts that made me concerned a little. a lot

[v8volvo]

An update to the above info:

For the hose that runs from the thermostat housing to the firewall, I now prefer this solution achieve the reduction and improved routing that limits risk of fuel damage to hoses:

Instead of seeking out a 5/8"x7/8" metal reducer, just order TWO of those abovementioned cheapo Rabbit hoses (PN above). Use the first at the rear of the head, and use the second in this position on the side of the engine. It connects to the tee (where the cold start thermostat return enters) and then provides the needed size reduction plus kicks the hose routing out towards the strut tower and away from the fuel pump. Then just use a direct 5/8" coupling barb to continue this hose to the firewall with a section of standard bulk heater hose.

Tip on that coupling (and also for the one at the back of the head connecting the Rabbit hose to bulk hose there): a brass 3/4" PEX union makes a perfect size, low cost, strong coupler for 5/8" automotive hose, readily found in the plumbing aisle at your friendly local hardware store.

I need to add pictures to this thread; will do that next time I get the chance.