Cautionary Tale - Aeroquip Pushlock hose

[mustanghammer]

I had a -10 Aeroquip Pushlock hose fail last weekend at the fitting. In fact it pulled off of the barb. Both the hose and the fitting were from Aeroquip. I have used pushlock hoses for years for fuel and oil with no issues. The hose connection that failed was relatively new (3 years) and gave no indications of an impending failure when it was inspected this winter. Also saw no oil leakage in a pre-race inspection. This type of hose uses the same AQP liner that is in standard Aeroquip hose. It is rated at 250PSI at 300F.

I will be running braided stainless steel from now on. If you are using pushlock you may want to add a hose clamp to each fitting - Aeroquip does not recommend this by the way.

[Knestis]

Pulled off or popped off? That is, what force motivated it to come apart?

K

[mustanghammer]

Good question but I am leaning towards popped off. It was the pressure line out of the engine to the first cooler. The hose was supported via adell clamps to another line. It wasn't stretched or in any tension.

[JeffYoung]

I don't use those things -- they always scared me.

Question -- did it happen on start during high oil pressure/low temps, or after running for a while?

[mustanghammer]

I don't use those things -- they always scared me.

Question -- did it happen on start during high oil pressure/low temps, or after running for a while?

Near the end of lap 1. The car was up to temp and pressure. I had run a full qualifying session earlier in the day.

The car took off to the right in turn 12. Thought it was a flat or that I had hit oil from someone else. Kept driving and trying to stay out of the way. Should have stopped:(

[tom_sprecher]

I don't use those things -- they always scared me.

+1. I have seen the standard hose ends hold on to the results of a crashes that should have been torn away.

[Chris Wire]

I don't use those things -- they always scared me.

I've never had a problem, but just about all the hoses I've done I've backed up with a hose clamp.

I think Aeroquip's non-recommendation about the hose clamps is half marketing and half tech-related. It doesn't do them much good to come out with a fitting that has to be helped out with a clamp. Logic suggests however, that including a clamp is safe, cheap insurance against the very thing that happened here.

FYI, the rotaries do run much higher oil pressures than a pistoni-type engine, but the range is 85-120 psi, which should still be well within the normal operating window of these products.

[lateapex911]

I was going to mention the possibility of a partial blockage or stuck thermostat, but, off the top of my head, that shouldn't be a problem with the pressure regulator operational....

[RX3]

I have also had this happen. You are at the uppers limits of the spec on the hose for temp. I use a hose clamp I don't care what they say it my motor. The oil coming out of the motor is about 300F

[planet6racing]

Me too. Hose clamps now back it all up.

[mustanghammer]

I have also had this happen. You are at the uppers limits of the spec on the hose for temp. I use a hose clamp I don't care what they say it my motor. The oil coming out of the motor is about 300F


Good point about temps - My oil temp gauge registers oil after it has traveled through two OE coolers. So it makes sense that it is hotter in the hose that failed than anywhere else.

FWIW - we remove the theromstats and insert a machined dowel to block off the bypass channel in the coolers. That way they are always flowing oil no matter what.

I ran solvent through the cooler last night - no blockage.

I'm going to braided lines....this is a PITA

[Chris Wire]

Good point about temps - My oil temp gauge registers oil after it has traveled through two OE coolers. So it makes sense that it is hotter in the hose that failed than anywhere else.

FWIW - we remove the theromstats and insert a machined dowel to block off the bypass channel in the coolers. That way they are always flowing oil no matter what.

I ran solvent through the cooler last night - no blockage.

I'm going to braided lines....this is a PITA

My guess is that what you didn't see during your cursory inspection is the hose aging from the inside out. Routine heat cycling at those temps, possibly helped by low winter temperatures, may have made the hose weaker on the inside with no indication on the outside. No way to catch it until it failed. Unfortunately, without a clamp as a fail-safe, the only likely outcome is the one you got.

[Ron Earp]

I don't think I'd mess with those things. I've heard about a couple of failures with them on www.gt40s.com. Making the braided hoses is a PITA and they are heavy, but at least you know what you are dealing with. Maybe these are best left on show and not go cars.

[joeg]

It's just a rubber hose on a barbed end.

You have a race car; use real race hose (braid with fitting). If you are concerned about weight, get some surplus Startlite on eBay and use it with AQP fittings.

Cheers.

[CCDangie71]

I've had one failure and since then I've used clamps with no issues. I'd prefer to use braided lines but had to resort to the pushlock as space was tight and wouldn't allow for braided lines and fittings.

I don't have much faith in the pushlock since they are engineered to work the same as Chinese finger cuffs. :blink: