Service tip - 4.0L SOHC cooling system - heater hoses

[cowboybilly9mile]

For those of you who opt to replace your radiator and heater hoses due to miles/age and in the name of vehicle reliability, I have, based on experience, a service tip to offer. The specific heater hose to be discussed here is located between the thermostat housing and the pipe assembly; some parts manuals may describe the subject hose as "pipe to engine - inlet", other may call it "pipe-1 to engine".

Based on recent experience and to ensure a leak free final result, you will want to replace this part with only a Motorcraft part. The Motorcraft part number is KHM-5, it's available on amazon, ebay and at Oreillys. Or for maximum cost, from a Ford dealer.

The reason for this is simple; if you use either a Gates P/N 28474 or the equivalent NAPA hose for this position, which is the exact same Gates hose, you can look forward to a leak where the (you cut to length) hose attaches to the heater pipe. The reason for this is because the Gates hose inside diameter is 3/32" larger than the OEM Motorcraft, despite the parts book saying it's the right part. Furthermore, the thickness of the hose is a bit more than the Motorcraft. These two physical features combined will make the OEM hose clamps and thus this hose harder to remove than the Motorcraft hose. Work space is precious; I wound up cutting the Gates up to get rid of it.

The other alternative to the Gates and the Motorcraft is a Dayco P/N B80400; this item is found at Autozone and many places online. The good new is that the inside and outside diameter of the hose are the same as the Motorcraft. The bad news is that the 90* bend radius is not nearly as tight as the Motorcraft; by using this hose (you cut each leg to length) you will be prestressing the pipe nipple on the top side of the (composite) lower thermostat housing. You can shoehorn that Dayco hose in there, but by doing this you are prestressing a thermostat housing that already has a sketchy service history and if you end up breaking it you will experience the thrill of replacing this part; it takes about 5 - 6 hours. Upshot is, when you do this you are asking for more trouble down the road.

The simple solution to all this? Buy the Motorcraft heater hose upfront, it has the correct bend radius and has the correct inside diameter and wall thickness for the application. You are not compromising the reliability and longevity of the t-stat housing, and you are not asking to replace the subject hose again (rework), which takes about 1 1/4 hours. Do be advised that your Ford dealer probably does not stock this, so plan ahead. Hopefully this thread will save someone the hassles I went through; live and learn.

Pics to illustrate the three hoses for the same app below.


^^^Motorcraft KHM-5



^^^Gates 28474


^^^Dayco B80400

[2001BLKRangerEdge]

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