Seeking suggestions: cost and complications for replacing coolant recovery hose

Hello all,

I have a 2003 Mazda B2300 with the 2.3 Duratec, and 198K miles. The engine still runs strong, but has developed a bad coolant leak in the dreaded "no can reach" zone behind the motor, above the bell housing and in front of the firewall.

It appears most likely that I have a leak in the coolant recovery hose or connection points. The hose assembly has two lines with connections in the no reach zone. Someone posted good pics on this or other forums (motor removed). The coolant recovery hose has a small branch hose going to the EGR behind the motor, and the other, larger hose that connects to a metal pipe piece that comes around and connects to heater hoses and/or recovery tank on the other side of the engine. The hose assembly is a Motorcraft KM4720.

This difficulty in reaching some hose connections is reportedly the result of the motor originally being designed as a traverse mount set up where all hose connections would have been reachable with no major hassles.

From what I've seen posted, it's either necessary to 1) drop the trans. to get to the spring clamp connection to the EGR to change out the hose; or possibly, remove intake and exhaust manifolds to gain access.

Can anyone suggest the least costly but adequate repair option? The work needed is probably beyond my skill and interest level to tackle. What would be a reasonable cost at a repair shop to do the job? The KM4720 hose is under $80, but there's lots of labor, apparently(?).

P.S., I'm considering selling the truck as a "mechanics special," as there's a fair amount of other deferred maintenance. I've already gotten 12 years of good use from this generally reliable little truck. If someone in San Antonio is interested in making a reasonable offer, I can be reached at 210-313-5788.

Welcome to TRS

Yes, rear coolant line on the 2.3l Duratec is a pain to change, simplest way is to pull out transmission
Shop time should be about 4-5 hours, basically the same as changing a rear main seal, which you should also have done at that time.
And any clutch work if a manual trans

So call around and get estimates on changing Rear Main Seal on your vehicle, the coolant hose will only take a little longer and cost of the part of course

Thanks for the good advice, RonD.

It's been 110K miles since the the last clutch/pressure plate/slave cyl. change, so those items would make sense to change in addition to the rear main seal, with the tranny dropped to replace the coolant hose.

I'm thinking this work would be around $1,500 if done by a reputable shop, and in addition to other items the truck also needs, I'm thinking now's a good time to sell it. Probably to someone who can do the work themselves.

P.S., I spotted this article on a possible upcoming new Ford small pickup that might arrive around 2022 (not the new mid-size Ranger coming next year).

"Ford reportedly considering small unibody pickup
Ranchero revival? Courier special delivery?"

https://www.autoblog.com/2018/07/27/ford-small-unibody-pickup/?ncid=edlinkusauto00000021&yptr=yahoo

I haven't tried it yet on my 2005 2.3, but it appears that if you could improvise a platform that allowed you to sort of lay across the top of the engine it would be possible to get up close and personal with those rear hoses.

I had the tranny out of mine a few years ago, thought I took pics but can't find them.

This discussion seems to offer some ideas to simplify :
http://www.therangerstation.com/forums/showthread.php?t=167572

Alternate method for changing coolant recovery tank hose KM-4720 AND KM-4556

P.S., I posted this in the archives section but posted here too in case you wouldn't find it in archives. I made a few slight changes to the one below.

Go to the original post to see a number of related pics:

http://www.therangerstation.com/forums/showthread.php?t=177814
______________________

Hello all 2001 and newer 2.3 Duratec 4 cyl. Ranger and B2300 owners:

Below I’m sharing some hard-won experience I gained replacing aged and leaking coolant hoses with connections or joints in the hard to reach area behind the motor and above the bell housing and transmission. I hope this will be helpful to a few of you with these Ranger/Mazda models that are at risk of having this hose failure. The leak behind the motor in my case happened several years after the almost inevitable plastic tee failure on the intake manifold side. Like many of you, I improvised a replacement metal tee connector from plumbing parts after the original plastic one split. That was a much easier fix than replacing the entire hose assembly described below.

There are several related threads on different forums I’ve linked below for reference:

https://www.ranger-forums.com/dohc-2-3l-duratec-mazda-l-engines-136/2001-2-3-coolant-hose-134714/

http://www.therangerstation.com/forums/showthread.php?t=177604&highlight=coolant+leak+2.3+duratec

http://www.therangerstation.com/foru...d.php?t=167572

For my truck (2003 B2300 with 5 spd. manual) I read and found several references to the coolant tank recovery hose (Motorcraft KM-4720 - pictured within the above links) often being a leak culprit. I didn’t initially see info. about other hoses in back of the motor and incorrectly made the assumption it was the KM-4720 that was leaking.

The biggest lesson I learned in the whole ordeal is that the other hard-to-get-to hose that’s under and behind the KM-4720 is the Motorcraft KM-4556 and it should always be replaced together the KM-4720! They appear to be equally susceptible to failure when old. The KM-4556 is about 18 inches long with bent ends, about one inch in diameter, and connects on a metal L branch nipple coming off the hardpipe water rail that terminates behind the motor, right under the KM-4720. On the front end, it connects to a metal nipple just behind and above the thermostat housing. I ended up having to mostly repeat a lot of the steps in order to change the KM-4556 that I initially overlooked and which was the actual leaker.

After seeing posts from JMarlowe and Soledad about the coolant recovery hose job being doable without removing the tranny, the intake or exhaust manifold, or the ac compressor, I decided to give it a try. My mechanical skills are moderate and I’ll say, having finished the job, that moderate or better skills will be required, along with a lot of patience and tolerance for working in extremely tight spaces. And BTW, if you’re a “big boy” with thick arms and hands, I suggest not even trying this particular approach;-)

And regardless of your physical size, those of you with above average mechanical skill, tools and equipment will likely find it easier to: 1) drop the tranny to get access, or 2) get access by removing the ac compressor and intake & exhaust manifolds.

For those of you, like me, who are unwilling or unable to change these hoses by doing aforementioned major components removal, here’s a suggested outline, similar what was provided by to JMarlowe and Soledad:

1. If you have access to an inspection camera, use it to try to conclusively spot the exact leak source behind the motor—in case it’s not either of the hoses, such as cracked head or metal flange/housing, that will require trans. or motor removal regardless. I ended up buying a $75 inspection camera with 38” long LED lit camera probe at Harbor Freight after my initial failure to correctly identify the exact leak source. I actually spotted some cracks/fractures in the metal (head or housings) with it, but fortunately, for now, they’re not leaking. The camera allowed me to see the dripping KM-4556.

2. If either the KM-4556 or KM-4720 are the source of the leak (and one or the other mostly likely will be), replace them both together. You will likely also need or want to replace a small hose (Motorcraft KH-56--mine got ruined during disassembly) branching off the KM-4720 near the exhaust manifold. The KH-56 connects to the heater vacuum bypass valve near the heater core. I also cracked the old plastic vacuum bypass valve during hose removal and it’s probably good to replace it regardless—the Motorcraft OEM part is only about $25.

3. Once up on jack stands, remove both front wheels and unfasten and peel back the flaps near the upper control arms on both sides, as this will allow much needed access.

4. It is recommended to use (buy, borrow, or rent) a specialty long-reach clamp removal/installation tool. In my case, I bought a $40.00 “OEM Tools” brand cable operated hose clamp pliers at Autozone. You may get by without one if you can successfully use spring hose clamps that will stay “locked open” before reinstallation. On the new KM-4720 I bought, it came with glued on spring clamps in the open position on the three hose ends. This allowed easier installation, but it was a challenge to use a screwdriver to snap closed the clamp on the small hose branch end that connects to the metal nipple behind the motor and above the tranny.

5. Like JMarlowe, I removed the middle exhaust section which connects with two 15mm nuts to the exhaust manifold, and two 15mm spring bolts to the back exhaust section (The two oxygen or CO sensors will also need to be removed unless you can separate them from their electrical connectors).

6. I unfastened the upper and middle bolts holding the dipstick tube, which is essential, but I wasn’t able to pull it out of the block, so I just worked around it.

7. Remove the two 15mm nuts on the exhaust manifold studs that are holding the metal pipe section of the KM-4720. Loosen hose connections on both ends.

8. Using a reliable jack under the tranny , remove the three 13mm bolts on each side of the tranny crossmember to enable lowering the tranny and crossmember by about 4 inches. At about 4 inches, the engine rests against the firewall and won’t drop any more. You will probably need this clearance for any hope of removing and reattaching hose clamps on the two hose connections at the back of the motor (one for each of the hose units).

9. After all hose connections are unfastened, you can eventually wiggle the KM-4720 out and through an approximate 1 in. space between the bottom of the exhaust manifold and engine block. In my case, I removed the old and also inserted the new KM-4720 from the exhaust manifold side of the undercarriage. I had to sharply bend the rubber part of the hose and tee that goes to the driver side connections, to get it to squeeze over the top of the tranny when reinstalling.


10. The KM-4556 is mostly positioned on the intake manifold side and should also be removed and installed from that side. NOTE: It will be easier if you install the new KM-4556 once the old KM-4720 is removed and before the new replacement KM-4720 is installed. And if for some reason you decide to position the KM-4720 in first, definitely don’t bolt it back on the exhaust manifold before the new KM-4556 is attached and clamped in back—to give yourself needed working room.

11. The only way I was able to detach the old and attach the new small hose segment of the KM-4720 on the back metal nipple was to lay down with my head pointed towards the front of the truck and reach around the tranny “barrel hug” style and do most of the work by feel rather than sight. You will likely get a fair amount of fiberglass into your arms from the disintegrating old insulation material on the firewall. Use a spray bottle with soapy water to ease getting hoses onto connections.

12. With the KM-4556 you can get a partial visual by shining a light into the opening on the driver side wheel well opening. But for that one too I had to get under and wrap both my hands around the tranny to force the new hose on, even with the expanded clamp and tool attached. The tool did not compress the spring clamp into a fully open position, and was also fussy about releasing the clamp to allow it to close and allow remove the tool.

So was all this effort worth it to save probably $600-800 in shop labor costs? I’m not sure, and it won’t be worth it to some folks who simply don’t want the hassle. The work took me 12 plus hours working in my spare time and I doubt I would ever tackle the job again.

I’m hoping the mistakes I made and learned from will be of help to those of you who decide to tackle this troublesome job.

Greg

Update: KM-4556 bypass hose seems to fit only 2001-2003 2.3 Duratecs

Upon doing some internet searching, I discovered that several sites such as the one linked below say the KM-4556 bypass hose only fits model years 2001-2003 2.3 Duratec Rangers and B2300s.

see:


For those of you with 2004 and later Duratecs, and who know what hose(s) take the place of the KM-4556 for those newer models, it would be nice if you could share that info.