i.d. of engine cooling hose form exhaust manifold to exhaust injection

[Peter]

HI all,

What size hose are you running from the exhaust manifold to the water injection point on the exhaust?

The injection point on my boat is a 1/2" i.d.

is 1/2" i.d. hose too small?

Thanks as always,

Peter

[Dave Neptune]

I've been using the 1/2" in SoCal for over 30 years withy no issues.

If you are running in very warm waters and are using a pump with more "flow" you may need to go to 5/8.

Dave Neptune

[Al Schober]

I think the key is to standardize. My cooling water lines are all 1/2" ID, fuel lines are all 5/16" ID.
The 1/2" water lines seem to move plenty of flow - fuel lines could probably be 1/4" without problems. I'm not changing.

[JOHN COOKSON]

5\8" here.
Tell us why you why you are interested in the hose size. Is it because you are not getting enough water flow? If the water flow is severely reduced it is not because of the hose size. Most likely there is corrosion in the hot section that is reducing the flow. Usually the corrosion build up is at the injection point or the manifold outlet. Also the pump may be marginal or if you are RWC mineral build up in the engine cooling passages.
If there is enough corrosion in the hot section to restrict the water flow most likely the engine is not performing real well.

TRUE GRIT

[Peter]

i have just installed this engine and while i was at it i re-did all the "plumbing" - fuel and water lines.

installed a fuel/water separator, all new fuel lines and a facet fuelpump

my old engine had a 5/8" hose off the manifold. when replaced it i also installed an anti-syphon loop. the hardware store i went to to get the fittings for this new line only had 1/2" hose barbs that would work with the fittings i already had, so i went with that . the rest of the cooling hoses are 5/8" so it is not all standardized.

i hope to fire it up tomorrow for the first time so i am not sure yet what the flow and temp will be like.

standardization - will make carrying spares simpler obviously. are there other good reasons for it?

i am in cold water - nova scotia.

"new" engine had a sherwood while old engine had an oberdorfer - i swapped them and installed a new impellor.

also curious about oil pressure. New engine had about 60 lbs on a new mechanical gauge. op regulator was screwed all the way in and stuck. swapped in the regulator from the old engine which is not stuck. did a no spark cranking test to make sure i would have op and it came up to maybe 40 lbs? is there any danger from op that is too high?

thanks,

peter

[JOHN COOKSON]

The recommended OP in the Moyer Manuel is ~ 40 PSI, engine fully warmed up, at your cruise throttle setting. When idling back the OP may drop to ~20PSI. When the engine is cold you may see ~ 50+ PSI. Sounds like you have the OP pretty well dialed in.
When you redid the plumbing did you do the THATCH modification - that is introduce the water into the manifold at its lower end? Search the forum byTHATCH to find the write up on it.

TRUE GRIT

[Peter]

i did not do the Thatch modificaton but had read about it. the thread i read did not come to a definitive conclusion one way or another on the efficacy so i did not do the mod.

a bit more research has now revealed another thread in which Mr. Moyer writes

"I applaud your idea of reversing the coolant flow through your manifold, and I feel a bit remiss in not doing so earlier (without the need to be prompted). It will no doubt eliminate trapped air that can collect in the front of the manifold, and I love the fact that it only requires a couple feet of hose to implement.

For now, and only because of our historical effort to retain the original appearance and function of the O.E.M. configuration whenever possible, we plan to hang on to the traditional setup in our exchange engines. We will however, enthusiastically endorse your modification along with any others that enhance the performance and/or maintainability of the Atomic 4."

I have not been able to find a thread that provides any data on the efficacy of the mod - have I missed that one too?

Peter

[joe_db]

Absent an IR camera, no way to know for sure that it helps, but it does make sense as far as purging air to run water uphill. I did it to my engine when I switched to FWC and the Indigo thermostat.

[thatch]

There is another side effect that is the result of running the hoses opposite from the factory setup. By injecting the water at the aft end (in a non v-drive model) it is attacking the manifold where the exaust gases from all 4 cylinders are passing by, rather than just the #1 cylinder as is the case with the factory routing. As the water flows toward the flywheel end of the engine, it's temperature increases, probably stabilizing the overall temp of the manifold. If this is actually happening, it would also mean that the intake runners are closer to being the same temperature which should make for a more even air/fuel mixture going to each cylinder. This theory would probably take some serious lab testing to proove, but it makes sense to me, at least on paper.
Tom

[sastanley]

I went to all 5/8" hose on my engine..mostly so I could carry one piece of hose long enough as a spare, but also to maximize flow and hopefully cooling. Other things I did was went to cast fittings when I could, and on a few occasions, put the hose directly on a nipple (i.e. a close nipple) as they have a bit thinner wall than hose barbs and allow more water flow..However, threaded pipe as a barb doesn't always seal well, so be forewarned.

These motors ran with 1/2" hose for years and years...however, I think the nipple on the Moyer bronze mixing elbow likes 5/8" hose. I seem to recall thinking that was another reasoning when I replaced mine several years ago.

Mo is up your way, but I have no idea how big N.S. is. He always tries to make himself available if you think you need something.

[thatch]

Like Shawn, I have changed to all 5/8" hose on my A4, both on the raw water and coolant sides of the engine. Stock 1/2" hose fittings measure less than 3/8" I.D. compared to brass 3/8" pipe nipples which measure 15/32" I.D. The O.D. of a brass or bronze 3/8" nipple or piece of pipe is right at 5/8" making it perfect for 5/8" hose. While converting my engine to FWC I cut several 4"x3/8" nipples in half to use as hose fittings. Not having ridges on these hose fittings actually makes it far easier to remove a hose when needed.
Tom

[Peter]

A HUGE thank you to all who have patiently answered my questions - many of which have no doubt been asked many times before!

Went to boat today and fired up the new - to me - engine. Started beautifully. Oil presssure dialed in at 50 lbs cold.

I used the following trick to eliminate any risk of water in exhast getting back into engine in case i had to crank a lot.

1) removed hose from water injection point and ran it to a bucket
2) plugged water injection point to prevent exhaust escaping there
3) used another hose to feed cooling water to engine from the bucket through the winterizing "T"
4) started engineand only ran it for a few minutes this way

rubber exhaust hoses got a little warm but not too bad.

It occurs to me this woud be a good way to do an acid flush at it is much easier to capture the water than through the transom.

Had a leak from the grease cup on the water pump which i could only stop by screwing the cup all the way in. I assume this means my water pump seals are shot. Checked oil and it was fine so i guess the inner seal held ok. will order a pump rebuild kit from MMI. I found a water pump extender bolt in a drawer on the boat so removal will be a dream.

Another trick i got from the fuel/water separator poll thread. filled the new filter with fuel and held it in a sturdy plastic bag - zip loc - to install. made me very confident i would not spill fuel into the bilge. will be a good way to change the filter in the spring.

Anyway, again, a big thank you to all for all the advice and guidance. hopefully will get launched this week and get some sea trials in.

Peter

PS - Nova Scotia is about 100 km (60 miles) wide and perhaps 700 km long. I think Mo is about 1 hour from my boat.

PPS - for those of you have been following my adventure, this is the engne i got for a bottle of rum. will have to chrisen it appropriately when the time comes! Captain Morgan Dark.

[ndutton]

A word of caution

No idea if you do but if you have a Vetus blow molded waterlift this is a very risky procedure. Vetus waterlifts are particularly intolerant of even the slightest overheating as in the case of no water injection.

[Peter]

trust me to find something not too smart to do...

i do have a water lift muffler but it is metal, not plastic as the vetus appears to be.

peter

[ndutton]

Roger that Peter. Maybe one of our Vetus equipped brothers will find this thread in the future.