Pump above water level - Primer pump needed?

[Richard L]

Are you putting the pump in the engine bay? The aquatec pump can prime from 3 feet up.


Aquatec states that:

POSITIVE INLET PRESSURE WILL INCREASE THE DISCHARGE PRESSURE BY A SIMILAR
AMOUNT, FOR A GIVEN FLOW. MAXIMUM INLET PRESSURE IS 60 PSI.

I cannot see how this can possibly work. the bypass pressure is set by a loaded spring. one end of the spring is at atmosphere pressure. Increasing the inlet pressure won't alter the outlet pressure.

If you are concerned about the reliability of the pump, follow the guideline and put the pump in the trunk. Did you read any of the warning in the box?

[utc_pyro]

Originally Posted by Richard L

Are you putting the pump in the engine bay? The aquatec pump can prime from 3 feet up.

Fender well simular to what Legacy_GT_Pilot did here: http://legacygt.com/forums/showthrea...38#post2497138
Thats an old aquamist based Perrin system. This location is fairly well shielded from heat and elements being outside of the frame rail, under the headlight, and completely covered by the fender liner and bumper cover.

Originally Posted by Richard L

I cannot see how this can possibly work. the bypass pressure is set by a loaded spring. one end of the spring is at atmosphere pressure. Increasing the inlet pressure won't alter the outlet pressure.

That would make more sense! So what they were saying was pressure would increase for the given flow rates up to the bypass pressure. Actual maximum pressure will not change.

Originally Posted by Richard L

If you are concerned about the reliability of the pump, follow the guideline and put the pump in the trunk. Did you read any of the warning in the box?

Yes I read the warning in the box: The system is designed to be TRUNK mounted. The pump and associated relay harness electrical connectors aren’t rated for external water exposure. The pump head should be below the bottom of the tank is possible. Methanol fumes are poisonous and should be vented away from the passenger compartment. A tall slim tank is preferred. Put the inlet on the back of the tank if possible. Higher than 50% mixes of methanol are a bad idea if you don’t take proper persuasions. Ect.

Car is an estate/wagon and both the underfloor and side pockets in the back are occupied by other equipment. The only area within the cabin left to locate a pump and tank would be under the dash, and that’s probably a worse for a lot of other reasons.

I fully understand any and all warranty is voided by installing outside of the recommended location. So any failure of the pump or related electrical harness is an already accepted risk and I’m prepared to replace those components as needed. To improve weather resistance: a vinyl pump cover has been installed, electrical penetrations sealed with liquid electrical tape, airgaps stuffed with dielectric grease, and the junction between the pump cover and pump head has been taped over to further keep water out. The electrical connectors are being swapped out with waterproof AMP connectors, and the relay swapped with a weatherproof one. Heat shielding to the fender well is also being upgraded, so it should stay cool-ish.

As the aquatic pump is a diaphragm type so inherently uses check valves to opperate and should in theory HOLD prime without issue. Not only that but the FAV should prevent air form getting in even if these valves had a slight leak.

My question was referring to does it hold prime over long periods of time in practice? There seem to be few installs that have the pump slightly higher without issue. But there was also at least one BMW 335i install where the owner was having prime issues.

The pump I was worried about reliability was the currently unused Koito centrifugal headlight washer pump in my european market washer tank. I only plan to use this if a primer pump + filter + check valve setup is required. I’m hoping the answer is “no not required”, but am prepared to rig it up if needed.

Thanks for the feedback on this (even if it's telling me to RTFM ), this kind of willingness from the vendor to discuss the technical ins and outs of a product is one of the reasns I went with an aquamist system!