repairing-fixing rubber engine hoses

Maybe 5 years ago I had a short section of curved 3/4 inch heater hose that was looking bad on the outside and also was somewhat weakened at the ends where it clamps to the pipes. Hose is about 8 inches long with a 90 degree curve and joins the head to the exhaust manifold for a FWC coolant system.

I decided to try something different from putting in a new hose section.
I wrapped the old hose with rubber friction tape from ACE hardware. I did not have a piece of steel spring lined hose and the bend was tight, a standard hose might have collapsed.

Result has been perfection, just like a new hose. The coolant system has a 7 pound cap, so does not see a lot of PSI. But I dont think it would have made a difference versus a 15PSI coolant system, it has been flawlessly leak free.

So I read up on rubber cloth friction tape and it has good heat resistant properties. One of my 3 inch wide exhaust hoses, the clamp end that attaches to the riser had developed a small tear and water would drip when running. So I removed the clamps and hose end. Then I wrapped with 4 layers of friction tape in an overlapping spiral pattern down the hose about 4 inches. Result is perfection, ran all day and looks and feels like new, no leaks.

This rubber tape is very sticky, has no stretch. Sticks very well to itself and other rubber hoses.

I also had some surface cracking on more coolant hoses and wrapped them also. I noticed some of these 'marine' engine hoses when they age form surface checking while the inner rubber lining is smooth.

So even if your thinking why bother covering old hoses with new rubber cloth skin, consider getting several rolls of rubber friction tape incase one of your hoses fails as it will fix the hose cheaply and quickly get you going again. You can buy an expensive silicon based hose repair tape, my experience is rubber friction tape works fine. The tape rolls I had used are 3/4 inch 30 foot rolls from ACE hardware, good price at $2.50 per roll.

 

took pictures to share how it looks wrapped with the friction tape.

exhaust hose


engine hoses, one wrapped other shows outer case cracks. the inside of these is fine.



another one

 

Friction tape has been used to repair and restore the sheathings on wires for generations. It's a fairly simple product, rubber over cloth and if bulked up on somethin, works pretty darn well against UV and water. I wouldn't test it with a lot of pressure, but 10 pounds or less might hold.

 

Have over 10 engine hours using that tape and still looks like when I put it on there.

 

Eventually, I'd think the cloth would break down, but a good quick fix type of thing to have around.

 

I will let you know.
The cloth fabric embedded in the rubber is cotton I think.

I repaired same small short hose that joins head to front of exhaust manifold one on the other engine over 5 years prior and has been ok that whole time.

I know the metal spiral reinforced hose is supposedly better. The boat has a lot of that but as it ages, it seems to crack the surface while the inside of the hose is perfect. My other hoses that dont have the steel insert, dont do that. So if you don't absolutely have to have it like on a suction hose, I suggest don't use it.

I replaced my suction hose for the gen with standard length of car heater hose couple years ago and it's so stiff, cant imagine it ever collapsing. My larger 1.25 inch raw water main engine suction hoses that run to the raw water pumps I did replace with marine wire spiral hose since I think that is best for that usage.

The pressure hoses on the engine cooling system dont need the steel spiral hose. Unless you have a very tight bend that the hose might kink.

That one exhaust hose I had to fix also has the metal spiral insert, while the other 3 exhaust hoses do not and have been fine.

 

hoses should be replaced at reglar intervals, the strength comes from the internal cord that will eventually break down. the cracking on surface does not affect the strength, the outter coating is there to protect the inner cords, eventually any exposed inner cords will start breaking down.

As pointed out, the metal reinforcement is only required where the hose has suction on it, it prevents the collapse of the hose on the low pressure side of the coolant pump.

I have not found any reliable way of determining the remaining life of the hose. I had depended on a visual and tactile inspection (if you squeeze the hose hard with your hands often you can feel if the internal cords are breaking down). I hate replacing hoses, or other engine parts, when they still have useful life in them. But sometimes when you buy a used vehicle or vessel you can not tell how old they are, nor the quality.

There is very large difference in the quality, I have seen factory hoses on Japanese cars last over 20 years, while the after market hoses give up in less than 5 years. Usually the better quality is cheapest to use in the long run, and they protect the engine.

A cautionary tale about coolant hoses: I had rebuilt the engine in my daughter's Honda CRX, replacing everything that was questionable, including fuel lines and many of the coolant hoses. Several years later, not long after I serviced it, and debated if I should replace the upper radiator hose (which looked and felt fine, but it was of unknown age). Just two days later it gave way without warning, ripped open all at once crossing the Texas desert, and resulted in severe engine damage. Those all aluminum Honda engines are very durable and reliable, but once badly over heated they are pretty much done and ready for the scrap yard. I had to replace the engine, and I did another complete rebuild on it. A replacing $15 hose could have prevented that.

So as an experienced engineer, and someone that has worked on all sizes and types of engines for over 40 years, I would caution you on trying to salvage old hoses by wrapping them with tape. It might make a good hose last longer, but it also makes it more difficult to tell the condition of the hose (which is difficult enough as it is). Using it as a temporary fix is an excellent use for wrapping the hose when you can not get a proper replacement. Or even as a precautionary reinforcement, but I can tell you from experiance it is not worth the risk of suffering severe engine damage to save on a questionable hose by depending on wrapping it with tape.

In a boat you not only risk severe (and costly) engine damage, if your engine overheats and conks out in a critical location, you could lose your whole boat, if not your life, before any one can come to your rescue.

And I have yet to find a reliable way to assesing the remaining life of a coolant hose.

 

Last weekend took the boat out for a few days running around. After 7 or 8 hours run time with engines from 1500 to 2000 rpm, and in some really rough water in places, with the stern and bow being buried in waves, that exhaust hose and the other water hose still looks same as when I wrapped it. And it did not leak a drop. I tugged on it and also still feels the same.

 

Updating the thread.
Friction taped hoses are all good looking still, no leaks, no degrading, tape is extremely well adhering. I wrapped some more hoses with friction tape.
I carefully looked at all my hoses on the engine rebuild and none were damaged on the inside. For some reason the outer rubber tends to crack on some brands of hoses, the inner rubber is still good.
I have some other brand of non labeled hoses and they are much older, likely decades older and yet still supple and good on the outside with no cracking at all. The ones that crack are labeled and have that colored stripe.
IMO hoses are deliberately designed today to fail and force you to think to buy new hoses, some kind of inferior exterior rubber covering is being used to fool you.
The much older hoses have a spiral wrapped appearance and also had some of the OEM color engine paint, so they could even be from 1970, but they are in perfect condition.

I rebuilt this starboard engine.
Getting the friction coated hose off the exhaust riser proved rather difficult.
The hose rubber had stuck very firmly to the bronze pipe.
So I finally managed to free it, but, I tore the friction tape and also tore more of the rubber hose worse than it was. So of course on startup it dripped raw water.
I decided to fix it, this time it is more like a new hose end.

First I removed the friction tape
2. cleaned the hose thoroughly with acetone.
3. mixed Black PL S30 polyurethane with 30-40% milled 1/32" milled glass fibers. Really makes this a strong rubber.
4. smeared on the outside of hose and in the ripped section.
5. use FG drywall tape, wrapped multiple layers around the hose end going back 4 inches, overlayering etc... and adding some more Black PL, fully saturating the FG tape, really any FG tape will work fine.
6. Did a final overcoat of Black PL and also an inner coat on the hose end.
7. Let it cure couple days.
8. To prevent future rubber hose sticking on, I smeared on Rector Seal T plus 2, onto fitting and the hose
8. installed hose and clamped it down and no leaks.

Hose end feels strong and tough, I think at least as good as new strength in quality.
Money cost negligible compared to new hose and I already had all the materials.

I noticed that many rubber hoses were very difficult to remove on this rebuild.
So looking at options, the Rector Seal T plus 2 white non hardening pipe dope seems worth trying.

I smeared it on all rubber hoses, RWC and FWC. It holds just fine under pressure. Hoses do not pop off, when clamps are tightened, you can not twist the hose. And when you remove the hose, the hoses do not stick, they slip off the fittings.

Sure beats ruining hose ends, plus who needs that aggravation of wrecking good hoses.
Rector seal T plus 2 has fibers in it which I think actually will help seal the fitting to the hose.
Products used
http://www.loctiteproducts.com/p/pl...-S30-Polyurethane-Roof-&-Flashing-Sealant.htm
http://www.rectorseal.com/rectorseal-t-plus-2/

Of course 1/32" milled fibers and drywall tape are common items.
I had discovered on my hull repairs that mixing Black PL S30 with 1/32 milled fibers created a really tough rubber material. it is just like a tire rubber, seriously.

Example picture, here is a very old hose, yet i prefer it. There is nothing wrong with the rubber anywhere inside or outside. Has some green paint on the hose. Hose has no stripe, no label, yet it does have a steel wire insert. The outer hose surface has zero cracking unlike the much newer labeled hose. IMO, the hose makers cheapened their outer rubber hose covers so that they age crack. Of course that will expose the inner steel wire to water, and then it rusts. Perhaps they did that to improve resale of hoses since the older hoses lasted forever, so a business decision, create good rubber insides and crappy rubber outsides to encourage people to buy new hoses.

 

Have you done a cost analysis of your time and materials vs a new hose?

 

Not really, I don't value my time on my own boat repairs. I do this mostly for the learning experience and It is my own free time. I dont work a regular job.
Fixing the hose end, estimate is about 30 minutes max of time.

The other end of this exhaust hose, to get to it would require me to remove the 12 gallon hot water heater, crawl back there and pry the hose from a large bronze mixer. I usually don't consider my personal time, I usually consider the monetary cost when doing things.

Ace hardware sells a 30 foot roll of friction tape for $2, normal stock in store item, best prices I have found.

 

My airplane has a 5 year rubber replacement per manufacturer's mandate, so I tend to use the 5 year rubber replacement on anything that could leave me stranded, my boat, truck, and cars
But the tape your using sounds like an excellent onboard must for that time your miles from shore and need a quick fix

 

Most rubber products have a 5 year R&R schedule associated with them. You can pull a brand new tire off the shelf, mount it on a rim and not drive on it for 5 years. After this time, they seem to magically degrade to unreliable.

 

Still working fine all rubber hoses I repaired.
No leaking, no cracking, no failing.
The Black PL polyurethane is very useful for all rubber repairs, sealing things up.

The sticky tar friction tape is also fine. Those hoses have a nice rubber inner liner which does not seem to get hurt by age. It is the outer liner that cracks and dry rots, hoses also have a steel wound spring between layers which adds strength to the hose, so I am just repairing the outer layer. Covering it up with that tape has held up fine. Other thing is my system uses a 7lb pressure cap, some are 14, so there is not a lot of pressure in the cooling system compared to others, dont know if that makes a difference really.
Updating the thread from years ago, have not bought new hoses except for the one on both engines coming from the main heat exchanger to the dual trans engine cooler which was really the wrong size and too short, a PO issue.

 

I always know how old the thread is if PAR is a contributer.