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Water pressure gage install on 500EFI's
Hi Guys. Did a search but couldn't quite find what I was looking for. As title says I'm adding water pressure gages to my 500EFI's and wondering where is the best location to tap into the cooling system.
Also what would be considered "normal" pressure at say cruising at 3000 rpm? Thanks! |
Many tap replace a drain plug with a threaded barb
The pressure depends on a few things: are you using stock bravo pickups? Transom mounted? Relief valve? 15-25 PSI is usually a safe bet for WOT and a good pressure to aim for |
The previous owner converted the water pick up from the drive to transom pick up and yes the pumps are just the stock ones that come on the 500EFI.
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I connected to Tee fitting on port side of block with mechanical gauge, 1/8 inch tubing
Cold idle close to 5 to 6, once thermostat opened would see 2 to 3 Cruise (36 to 3800 rpm) around 25 with new impeller, WOT a bit more 509 MPI, bravo pickup and Merc pump |
As others have said…we use drain plugs on block.
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Thanks all. Gages are still being shipped and include the polyethylene tube. Didn't realize the pressure was as high as mentioned. I assume the hose uses a clamp to the barbed fitting? Definitely wouldn't want that line to blow off. Was thinking those shark jaw type fittings used with polyethylene plumbing may be the ticket unless screw style clamps are sufficient.
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I used 1/8 inch air brake line with brass compression fittings. No chance it will come off
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Yeah that's a great idea too!
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On my old boat it had the reading taken from the block drain, it would constantly clog.
On my 502mpis, the fittings are in the T stat Housing. Never had a clog in 16 years. The TStat housing or intake manifold are better locations IMO. You should see 1-2 psi at idle, 10-20psi at cruise rpms and 20-30psi at WOT |
Originally Posted by Griff
(Post 4863957)
On my old boat it had the reading taken from the block drain, it would constantly clog.
On my 502mpis, the fittings are in the T stat Housing. Never had a clog in 16 years. The TStat housing or intake manifold are better locations IMO. You should see 1-2 psi at idle, 10-20psi at cruise rpms and 20-30psi at WOT |
Based on the input above regarding using the block drains and how hard it is to access them, etc. I've decided to drill and tap the thermostat housing. Aside from avoiding drilling into the thermostat itself are there any other things to watch out for? Does it matter what side of the thermostat I tap?
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I just finish installing mechanical pressure gauges on my HP500's. Block drains, forget that. I tapped the intake left of the therm housing where there was an unused accommodation for a sender.
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I have 1-2 psi at idle, 10-12 at 3500-4000 and 18-20 at 5500 . Anything over 30 you may start pushing water out between the head and block and intake . Here’s my 500efi at 35psi you can see where the water stains/rust was pushing out water.
https://cimg8.ibsrv.net/gimg/www.off...ac0d3d1df.jpeg |
Don't have a pic do you?
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pq what thermo housing do you have post a pic
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Man what a rookiie. First time trying to upload pics on here. Anyway not real easy to see but on the left lower (below the thermostat) is where I plan on drilling and tapping.
https://cimg3.ibsrv.net/gimg/www.off...1fc60e8ceb.jpg https://cimg5.ibsrv.net/gimg/www.off...18229c6883.jpg https://cimg7.ibsrv.net/gimg/www.off...160cb53143.jpg |
sorry I didnt see your first post being 500 efi, that should work
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