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View Full Version : Crossover back to original circulating pump....



HOWARD O
02-18-2009, 07:33 PM
I've had it with this cooling business and have decided to just go back to the original setup, complete with circulating pump and all those hoses. I don't care what anybody says, these crossover systems are just not worth it!

Anyone have a good source for these parts, new or used, for an early '80's 454/330?

Air 22
02-18-2009, 08:05 PM
Howard....I agree with you...my Stock Merc 454Mag so no performance gain by removing the circ pump and using the crossover. My mechanic said what many other's have said it can create steam(hot) pockets etc due lack of consitent water pressure maintained during all rpm ranges...not good:eek:
note the discussion on OSO...most would NOT do it unless ur talking blowers etc....
http://www.offshoreonly.com/forums/general-q/183518-mercruiser-502s-water-pump-pass-2.html
Turn key is key...lol:kingme:

Check with Madpoodle for merc parts..he's Da Man....:)

HOWARD O
02-18-2009, 08:22 PM
Oh, I really agree with you, just ain't worth it. I could get by and really wouldn't much care with this old motor if it were summertime.....but you know how cold the water is here right now and I want to use the boat! Can't blame the previous owner, Cuda, he lives in warm waters and never had an issue with his Formula with no t-stats. My old 16 hasn't had one either, but my brother owns it and uses it in SoCal. Not the greatest way to go, but it just turned 40 yrs. old and hasn't been an issue.

I have been chatting with Madpoodle about crossovers and such, but not about going back to original equip. I guess the first thing I should do is contact Cuda and see if he still might have the old stuff.....I'd surely buy it off him!

I'll tell ya what, I was eyeing your old motor BIG TIME, but that kind of investment is down the road right now financially. That would've been a perfect repower for me though! :yes:

Air 22
02-18-2009, 08:37 PM
Oh, I really agree with you, just ain't worth it. I could get by and really wouldn't much care with this old motor if it were summertime.....but you know how cold the water is here right now and I want to use the boat! Can't blame the previous owner, Cuda, he lives in warm waters and never had an issue with his Formula with no t-stats. My old 16 hasn't had one either, but my brother owns it and uses it in SoCal. Not the greatest way to go, but it just turned 40 yrs. old and hasn't been an issue.
I have been chatting with Madpoodle about crossovers and such, but not about going back to original equip. I guess the first thing I should do is contact Cuda and see if he still might have the old stuff.....I'd surely buy it off him!
I'll tell ya what, I was eyeing your old motor BIG TIME, but that kind of investment is down the road right now financially. That would've been a perfect repower for me though! :yes:

Good luck in ur search...sounds like u have a plan:wink:...My 502 has a new home in MI now...the guy had a 454/330HP...so the 502/415HP should be a nice improvement..:)

HOWARD O
02-18-2009, 08:41 PM
Thanks, I'll get it all worked out eventually. I'm just anxious to be using the boat!

It went to a 454/330 guy huh? Guess we were in the same boat.....so to speak. That's great.....nice, solid motor. Your new one is in a different league altogether though! :shocking:

mjw930
02-18-2009, 09:06 PM
Why don't you simply convert to a bypass system that includes the thermostat?

http://www.stainlessmarine.com/images%5Clg699306818.jpg

With this kit the cooling within the block is exactly the same as with a water pump. I've run this setup with water pressure gauges and never had a problem like the guy claims to have in the OSO post so I don't know what he's smoking but then I never run the motor past idle until it's fully up to temp and the thermostat opens. Don't over analyze this, it's really quite simple.

Lenny
02-18-2009, 09:08 PM
I have what the picture above depicts. I love it :yes: Not a single issue. None, notta, nothing...

SSM on a small block (x 2)

Air 22
02-18-2009, 09:49 PM
Why don't you simply convert to a bypass system that includes the thermostat?
http://www.stainlessmarine.com/images%5Clg699306818.jpg
With this kit the cooling within the block is exactly the same as with a water pump. I've run this setup with water pressure gauges and never had a problem like the guy claims to have in the OSO post so I don't know what he's smoking but then I never run the motor past idle until it's fully up to temp and the thermostat opens. Don't over analyze this, it's really quite simple.
MJ...No offense..but the crossover does NOT provide the same consistent block pressure as a Circulation Pump.
The circulation pump serves for maintaining a uniform flow of heating water through the block even at low engine speeds...Like you said..." its quite simple"...lol
I had that same system u posted from Stainless Marine but saw no gain on a STOCK motor. Looks cool, sure they will tell ya anything so u will buy it...:) u and many others have had good luck with it but just the same some have not had any luck...that being for many reasons. I wish I had some luck w my old 454 with the crossover...it was prob too tired to realize any benefit...:nilly:

Lenny
02-18-2009, 09:58 PM
So Dwight, with a crank mounted pump (Jabsco) AND a thermostat, where is the difference?

The thermostat opens and it closes. There is a pile of pressure behind it from the sea water (crank) pump (Bravo). If there was a circ pump there and the thermostat was closed what is the difference between that and the raw water pump and the thermostat closed and then opening ???

Just a question.

HOWARD O
02-18-2009, 10:15 PM
FWIW, I do believe a crossover with a bypass will serve my purpose just fine. I'm really not trying to "over analyze" anything, just using plain economics. I have tried to find a used bypass crossover parts and have struck out. I "think" I can probably find used original plumbing parts way cheaper than a new, $300 bypass kit.
Here is a very interesting read that was posted by "CFM" at this thread on Speedwake (http://www.speedwake.com/upload/showthread.php?s=&threadid=25901&perpage=20&highlight=drilling%20thermostat&pagenumber=1). I hope the mods here don't mind because I think it contains valuable information. Take from it what you will, but it's a fun read nonetheless:
Ah, I need good photos to show this stuff. Anyway, here is some stuff.
BTW: get ready for a long one. I need video/audio conferencing with you guys - would be much quicker.
1) The Merc sea water pump is a very stout unit and will be able to supply more water than any engine could ever use.
2) A restriction to water will cause psi. How much psi depends on how much of a restriction to flow there is.
3) A water crossover without a bypass will deadhead the cooling system at the t-stat when the t-stat is closed. Result - way too much pressure. I saw 40+ psi on the dyno in this fashion but with two holes in the t-stat to relieve some pressure.
4) A water crossover must have a bypass if using a t-stat so that the sea water pump is not dead headed. This should lower pressure right? Yes. But not enough. How can you expect a -10 (.625") or a 3/4" hose to flow the same as the 1 1/4" sea water pump running at full tilt with t-stat closed? You don't. I ran this too and found water psi to hit 35-40psi. Better, but not good enough. Still way too high.
5) This leads to removing the t-stat. Damn! Did not want this because of running it this way last time it was in the water. Coolant temp would only go to 120-140 under full WOT for a while, as as soon as the throttle was let up the water temp would disappear cold. This was in 70+ degree water. When in 50+ the temp guage never moved. Anyway, did this on the dyno and only saw 10-15psi at times - if that. Too low of a psi isn't good either but 15-20psi is right where you'd want it for steam pocket , combustion chamber, cylinder wall,and etc cooling reasons.
6) Back to the drawing board. I want a t-stat so I can keep some temperature in the motor. I'll talk about cold water, hot engine parts in a while. Yes, I saw bad stuff with this also.
Put T-stat back in, with two small (3/16") holes drilled in it, and re-install bypass. What did I do different this time? Installed the Merc bypass valve. Yes, it works! Regulated the system to 28-32 psi.
7) Done - Finally! No. I wish. Still too high of a psi for my blood. For those of you like me that have aftermarket heads or ported factory heads realize that there really isn't any intake gaskets that have some sort of beading or seal around the ports. You use gasket sealer and Gorilla Snot (that's what we call the yellow stuff) and hope it will stand up to the psi. Guess what - it may or may not and if it does it probably won't hold up for that long. Believe me, I know. More on that later.
8) Although I haven't checked it yet, as most of us know I'm still doing my dyno thing and haven't been back in a while - is the psi on the stock system. Many have reported lower psi's in the 25 and under range. Apparently no issues. Why is that? I'll tell you - this is where I need more pics but I'll try to explain. So here comes -
9) The sea water pump feeds water into the factory t-stat housing by means of the large inlet on the right. I takes a right turn to the back and then at the back it u-turns back up the left to the front. In the back there are a few holes to let some of this water raise up into the chamber that the water outlets to the exhaust are. This chamber is also where the t-stat (when open) feeds into. Yup, two chambers - well thought out I must say. Okay, back to the front - the cool water then enters the very large outlet that connects to the hose that goes to the recirculating pump. The rec. pump is a real pump, therefore it is drawing water from this area - the significance is that it is reducing pressure here since it is pulling, not pushing here. Remember, the t-stat housing also bleeds some water thru to the exhaust which is open to the atmosphere and thus water psi reduces here also. Ahhh, so this is why this system has lower psi than the others! Yes, sir. Smart engineering!
Whew! getting long? Yup! Not like I really like to type vs talk but many will read this, so let's go further.
The water get's pulled in thru the rec. pump and then get's pushed thru the block, heads, etc. So, what if the t-stat is closed ? Ahhh, the water slows down, almost stops, and farther back the water is going into the upper chamber of the t-stat housing and out the exhaust. Remember?
It's really an ingenious system.
Now, why go to a crossover?
1) Big hp motors have big superchargers. With the SC drive system there is very little room or no room for the rec. pump and it's pulleys and belts. Hmmm. So what now? Well, we have the sea water pump pushing the water thru so we can get rid of the rec. pump. Now what? Get rid of the t-stat completely or use an open washer to reduce a little water flow, add an intercooler and dump, and then add a psi reducing regulator valve so the system doesn't over pressurize. That works. Well, for psi reasons anyway. So, the motor doesn't get up to proper temp (BAD) but the water psi is fine (good) and the cylinder heads are kept much cooler (Good) and everything fits and we have a working cooling system to keep things from overheating (Good) - here the "Goods" outweigh the bad so this is how it is.
Why would a naturally aspirated engine with room for a rec. pump not use one? We don't know any better since the we all know the seawater pump can push way more than enough water thru the motor. I said we, which included myself until recent times.
I know how much hp a rec. pump "ZAPS" because I've dyno'd many motors with electric water pumps for race cars and street cars. It is very small and only noticeable when the engine is starting to turn some serious rpm. So, forget about the hp loss. You lose way more driving with your head above the windshield at speed.
I've found bank to bank water flow issues with some styles of crossovers and I've found some major condensation issues with cross overs and I've found (as I've talked about in great lengths above) some major psi issues with crossovers if the system isn't designed/installed correctly.
Can cross overs work - you bet ya. I have many designs in my head that can work well, but some require different and bigger dollar psi relief valves and some with multiple valves and use of multiple stage water pumps.
Closed cooling? Looks better and better the more I look at it for engines that have room for a recirculation pump and cooler.
Lastly for now - I've kind of lost my place i think because I've been typing for a while , while still thinking about this and work related projects at the same time.
I may have made some mistakes above and will proof it time to time and add some more input on this subject. But you are probably almost asleep by now and I want you to have energy to think about this stuff. It is important and good stuff to know.
Hope this helps -
Someone who unintentionally started to learn this stuff but glad he did. I think.

Air 22
02-18-2009, 10:20 PM
So Dwight, with a crank mounted pump (Jabsco) AND a thermostat, where is the difference?

The thermostat opens and it closes. There is a pile of pressure behind it from the sea water (crank) pump (Bravo). If there was a circ pump there and the thermostat was closed what is the difference between that and the raw water pump and the thermostat closed and then opening ???

Just a question.

Lenny....The issue doesnt seem to be when the engine is cold..its when its hot and @ varied RPM's the block pressure maintained is not as consistent without the circ pump....If the sea water pump(crank) (Bravo) is all thats needed I guess GM and its engineer's are wasting r time? Maybe the question should be...Why doesn't say Mercuiser equip their STOCK engines minus the cir pumps?

Looks like Howard posted some good info..:)

mjw930
02-19-2009, 07:18 AM
Flaw in the theory: circ pump is a centrifugal style that does not develop pressure. The pressure you get in the system is from the raw water pump until you get up to speed. Eventually the flow of water through the pickup over rides the raw water pump and your pressure is derived from the motion through the water. As far as the steam pockets thing, it also happens in stock engines, don't let anyone kid ya. Unless you have the crossover plumbing on your manifold, you are going to get pockets back there..
The crossover is not a HP maker, anyone that tells you that also has a bridge for sale. But, it does eliminate a problem prone part on your engine. And it looks good :) :)

You beat me to it. I never claimed it would provide any performance improvement and I suggest it to Howard since he does not have a circ pump today and instead of adding one he could simply swap out the one phase crossover he has with this unit and not have to deal with all the extra hoses, pulleys and belts.

As for the steam pockets, I used the rear water ports on the intake manifold and plumbed hoses from the rear to the front to assist in top end recirculation, it worked perfectly. If I recall correctly that's exactly what Merc did on the HP500, even with the recirc pump. You can also play with the port sizes on the exhaust water dumps to adjust for pressure issues. At idle your pressure will drop but as long as you have flow and can evacuate the rear area of the motor you're fine. Once you reach speed and RPM's the system pressure should stabilize if everything is sized correctly. I know I never had any issues at speeds up to 85 mph and RPM's bumping 6K.

VetteLT193
02-19-2009, 07:34 AM
Howard: Put a wanted post on OSO/Serious/boatfreaks/here and you'll probably get a waterpump setup for next to nothing (used).

On another note: After taking the pump out I'd be hard pressed to go back. Sucker weighs a ton and looks like crap.

I really like having 1 less belt and one less replaceable part. The water pump setup had hoses all over the damn place, which is another point of failure.

BigGrizzly
02-19-2009, 10:11 AM
Well, I will defend the circ pump. The steam pockets is primarily on small blocks. Big blocks always run hot on one side with a crossover, hence I had a restriction in mine before the CCooling system. I did the block matrix thing thing with a thermo gun, bad news especially for my procharged one. The pluming is the simple part of a circ system. If the crossover is restricted properly it isn't too bad. Miami guys don't count because of ambient temp and humidity. Most people do not have too many problems with crossovers. One small point if the raw water pump goes the circ pump actually serves in a minute fasion ti save the engine. My sun lost the raw pump but that darn engine kept pumping enough water to get home. Motor was hot but no issues.

gcarter
02-19-2009, 11:54 AM
I had a crossover AND a circ pump.....

http://www.donzi.net/forums/attachment.php?attachmentid=34764&d=1205500979

Lenny
02-19-2009, 12:03 PM
That's the San Juan system isn't George ?

gcarter
02-19-2009, 01:14 PM
That's the San Juan system isn't George ?

Yep, it is.
My next one will be remote, but otherwise very similar.

HOWARD O
02-19-2009, 02:16 PM
Well, I do have a bid on a kit on ebay....although the t-stat housing doesn't appear to have a bypass fitting. Guy claims he's using the plugged port on the manifold on the side....near the t-stat. I can make something out of it for the price!

I may eventually head back to a circ pump, but with spring and summer approaching, it'll probably on the back burner.

Now I need to concentrate on saving nickels and dimes for a new, closed cooled repower! A nice, used 502 would probably suit me just fine!

By the way, the boat runs GREAT!!! Here I was worried about it being over propped.......now it feels like it blows by 4600 so fast that I'm thinking about another prop! But nah, probably healthier for the engine and tranny the way it is.

Oops, hope that didn't just start another 5 pages! :kingme:

lee
02-19-2009, 02:52 PM
This is the exact set up i'm looking for anybody have a part # and maker
why don't you simply convert to a bypass system that includes the thermostat?

http://www.stainlessmarine.com/images%5clg699306818.jpg

with this kit the cooling within the block is exactly the same as with a water pump. I've run this setup with water pressure gauges and never had a problem like the guy claims to have in the oso post so i don't know what he's smoking but then i never run the motor past idle until it's fully up to temp and the thermostat opens. Don't over analyze this, it's really quite simple.

VetteLT193
02-19-2009, 02:54 PM
This is the exact set up i'm looking for anybody have a part # and maker

Stainless Marine. check their web site.

Air 22
02-19-2009, 08:19 PM
Well, I will defend the circ pump. The steam pockets is primarily on small blocks. Big blocks always run hot on one side with a crossover, hence I had a restriction in mine before the CCooling system. I did the block matrix thing thing with a thermo gun, bad news especially for my procharged one. The pluming is the simple part of a circ system. If the crossover is restricted properly it isn't too bad. Miami guys don't count because of ambient temp and humidity. Most people do not have too many problems with crossovers. One small point if the raw water pump goes the circ pump actually serves in a minute fasion ti save the engine. My sun lost the raw pump but that darn engine kept pumping enough water to get home. Motor was hot but no issues.

Randy...Longevity is key:wink: ... They (Crossovers) are only good if you eliminate the thermostat and run restrictors, then you essentially shorten the life of the engine trying to get it to run consistent temperatures throughout the cooling paths....:nilly:

BigGrizzly
02-20-2009, 12:20 PM
Air22, has been doing his home work:wink: If I didn't know him I would be impressed, what do you expect from a pilot.:yes: