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Coolant pressure test Kit for Crusader 5.7 MPI

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dfswan

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Anyone know of where I can get a coolant pressure test kit for a Crusader 5.7 MPI 2004? I went to a few Autopart stores, but the kits were not compatible.
 
I removed the temp sensor from the top left of the intake manifold (a pipe thead, either 1/4 or 1/8 - don't remember) and replaced with a $10 pressure gage. Did my tests at the dock. It is accurate, foolproof and cheap.

Cabojohn
 
Usually the auto pressure testers work fine...you just need to get the full kit with the correct adapter or 'borrow' the basic tester and buy the correct adapter....fastest approach is to take the degas bottle's cap and tell them its from the system you want to connect the pressure tester to...
 
I wish the auto places around here had the correct adapter. I couldn’t even find one online.

I used Cabo-John’s idea of removing the Temp Sensor. It worked pretty well but the degas bottle cap kept releasing at 12 PSI. The system came down quickly to 10PSI and then held there loosing about a lb over the next 45 minutes.

Does anyone know what the pressure is supposed to be. On the CAP there is a 75 kPa WICH equals about 10.8 PSI

Makes kind of hard to test at 15-18 PSI with this method.
 
I have sold my 5.7, but as I recall that the pressure cap is supposed to maintain 7 psi so it sounds like you are doing fine. You should check your specs.
If you shared your thinking on why you may have a problem then perhaps you could get some better suggestions.
The key to making this system work is to get as much air out of it as possible before capping it and going through several heat cool cycles. This will expel the remaining air and then all should be good.

Good luck!
 
The operating pressure of the cooling system has been tweaked as time evolves so I'd be incline to trust the cap (assuming you know it is original). Based on your measurements, the cap appears to be functioning fine.

you can always block off the degas bottle and that will eliminate the cap opening early...if you want to test it at say 12PSI (i wouldn't go to 18 PSI)...another option would be to get a different cap for testing.

Concur on John's suggestion as to sharing the details...

If you have the details on the thread size of the cap/degas bottle, I can likely find a viable adapter using the stant catalog...
 
Thanks for the feedback. I would like to find the adaptor for the Crusader Degas Bottle Cap. The cap is:

marineengineparts.com

Crusader Marine R034045 Cap, Degas Bottle

Crusader Marine R034045 Cap, Degas Bottle
marineengineparts.com marineengineparts.com

Not sure what the specs are on the thread or size.

Here are my details:
Had a wet cylinder 6 and it was determined that I had a leak in my Exhaust manifold. I replaced both manifolds and risers. When I went out for my test run, I filled the coolant to about halfway up the degas bottle and I took her (Shamrock 240 WA) to a small lake and cruised under 2000 RPM for about 5 miles. I checked the degas bottle and it was almost to the top. I figured that was due to expansion and was pretty pleased that I had solved the leaking problem. I came back around 3400 RPM and opened her up for a bit to check TOP RPM, Speed, Prop... again around 5 miles.

After I got her back on the trailer, I checked the degas bottle and it was empty. As I mentioned above, I did a pressure test using Cabojohn method of removing the temp sensor and putting in a temporary gauge and air valve. Pressure was steady for more than 10 minutes but since I could only get the pressure up to about 10 PSI, I'm not sure how conclusive the test was.

I would love to think CaboJohn is correct in thinking there was a large air pocket in the system and that was the cause of the low level in the degas bottle after a hard run. If that is the case, my problem is solved, and I can thank you guys for the results.

If not, I may have either a Heat exchanger or internal problem. I guess the HE would be the best of those problems. I was going to remove one of the caps from the heat exchanger and test, but since I couldn't get the pressure above 10 PSI and there was no leak, I either need to increase the pressure with a correct adaptor, or closing off the degas bottle (two openings) to see if I can get a drop in pressure, or take it out for a longer test with plenty of antifreeze to see if I can get it stable.

...now aren't you sorry your asked for more detail? 😂
 
If the cap opens at 10 PSI, the system won't see any operating pressure above it....so watch what you wanna try.

I have yet to see a FWC engine that didn't need a 'burp' or two once the coolant was refilled. Usually, its easiest to run the engine, boat in the water, until it comes up to operating temperature...then let it cool...if the level in the degas bottle drops after cooling off, refill it, again, and repeat the temp cycle...some installations are optimal and will purge the air real quick...others will take a few cycles...I'm sure a vacuum pump would help but you'd need an adapter for that as well.

the part number yields no info regarding the thread size...best bet may be to take the cap to a good independent garage in your area with a full set of PT adapters...next best would be one of the big box auto parts stores with the loaner program...assuming the have a full set of adapters.
 
Ditto on Mark's comments. When the engine heats up and the coolant expands, if it is truly full (no air bubbles), the pressure rises very quickly (liquid is not compressible although the hoses will expand a little), the pressure cap will open and the excess goes into your overflow reservoir. After that, nothing happens no matter how long you run. Upon shut down the engine cools, the coolant shrinks and pulls a vacuum and sucks coolant from the reservoir back into the engine.

If you have an air bubble it provides a compressible space in the system and the pressure will rise more slowly as the engine heats up and if the bubble is big enough, the system pressure may never reach high enough to open the pressure cap. This may be one reason we don't see 15 lb. caps on these systems. But it will reach enough pressure to open the cap with a moderate or small bubble, and if the system is well designed (this has varied over the years) the air bubble will have lodged next to the opening cap and some or all will be expelled. Upon engine cool down liquid will be sucked in to replace it.

So it sounds like your system is working and as Mark points out it may take several heat cycles to expel all the air. If you want to speed things up one trick is to remove the pressure cap on the cold engine and squeeze the large hoses and try and milk the bubbles up to the top and then add coolant to replace. This works remarkably well for getting the air content low enough that you can then get the system right with minimal heat/cool cycles,

Good luck!
 
makomark said:
If the cap opens at 10 PSI, the system won't see any operating pressure above it....so watch what you wanna try.

I have yet to see a FWC engine that didn't need a 'burp' or two once the coolant was refilled. Usually, its easiest to run the engine, boat in the water, until it comes up to operating temperature...then let it cool...if the level in the degas bottle drops after cooling off, refill it, again, and repeat the temp cycle...some installations are optimal and will purge the air real quick...others will take a few cycles...I'm sure a vacuum pump would help but you'd need an adapter for that as well.

the part number yields no info regarding the thread size...best bet may be to take the cap to a good independent garage in your area with a full set of PT adapters...next best would be one of the big box auto parts stores with the loaner program...assuming the have a full set of adapters.
Click to expand...
Good to know about the 'burping' of a FWC engine. I'm definitely going to do your hot cold cycling to get rid of any air pockets in the system.

As mentioned above the cap has a 75 kPa which equals about 10.8 PSI. That is about right for when it released pressure (and made a mess). What would think of putting a plastic wrap between the degas bottle and the cap and bringing the pressure up to 15-18 PSI? As long as I'm careful about the pressure, it should work.
 
I suspect your last comment crossed my last post somewhere in the ether and you wrote before reading the pressure/air bubble discussion. But in answer to your query about plugging the exit and going to 18 psi, if you still have a large bubble in the system you might sneak up on that pressure and learn that your hoses are good that far. That is most likely true in any case since automotive versions go to 15 psi regularly. But, if it turns out that your previous effort got all the air out of the system then the pressure will rise nicely until the hoses expand to their limit and then, since the incompressible fluid continues to expand and has nowhere to go, the pressure will soar quickly (in way less than a minute) to whatever level (50 psi, higher??) that is required to cause one of the hoses to burst or the intake manifold to crack, or some other real disaster.

Not a test worth running in my judgement. Better to continue to operate and see if the coolant levels stabilize. I would bet they will. If you find continued coolant losses then figure out where it goes (exhaust, bilge or oil....there are only three possibilities). Once you know that then post the issue and you will get lots of opinions on what to do next. we have all been there. That's boating.

Good luck!
 
CaboJohn said:
I suspect your last comment crossed my last post somewhere in the ether and you wrote before reading the pressure/air bubble discussion. But in answer to your query about plugging the exit and going to 18 psi, if you still have a large bubble in the system you might sneak up on that pressure and learn that your hoses are good that far. That is most likely true in any case since automotive versions go to 15 psi regularly. But, if it turns out that your previous effort got all the air out of the system then the pressure will rise nicely until the hoses expand to their limit and then, since the incompressible fluid continues to expand and has nowhere to go, the pressure will soar quickly (in way less than a minute) to whatever level (50 psi, higher??) that is required to cause one of the hoses to burst or the intake manifold to crack, or some other real disaster.

Not a test worth running in my judgement. Better to continue to operate and see if the coolant levels stabilize. I would bet they will. If you find continued coolant losses then figure out where it goes (exhaust, bilge or oil....there are only three possibilities). Once you know that then post the issue and you will get lots of opinions on what to do next. we have all been there. That's boating.

Good luck!
Click to expand...
Thanks for your reply. After some thought, the pressure cap releases from the seal, so covering the degas bottle with plastic wrap and putting the cap back on, wouldn't do anything. I understand the concept of compressed air (Spring) vs uncompressible fluid. FYI, I put the air in with a separate tank of only 18PSI, but I agree with you about getting the air out and see if the problem really exists. I'll keep working on an adaptor for the Degas bottle, but that won't be my next action. I'm taking the boat out today to see if I can get the air out and see if the level stabilizes.
 
I did my best to get the air out of the system. Ran it for about 30 minutes under 2000 RPM, everything stable. Stopped and started multiple times, let it cool somewhat, and opened the cap. Same as before, everything is fine as long as I keep the RPM below 2000, but when I push it, even for a short time, the coolant drops about a pint.

I guess I'm going to have to isolate the degas bottle and plug the two hoses that attach to it to increase pressure to about 15 PSI. I'm also going to run a CO2 test after it is under load. I did an idle and the CO2 was absent.

Suggestions to take the cap to an auto parts store were totally fruitless. They have no adaptors, online or otherwise, that will fit this. I'll contact PCM directly to see if I can get any assistance. Even my marine mechanic ends up bypassing the degas bottle.

I still have the same options as before. If I can get the pressure test, I can at least eliminate the heat exchanger, leaving a cracked head, or a head gasket. Since I don't have coolant in my oil, I think my block is OK. but who knows.
 
I am confused. I really don't understand the problem (if there is one) and don't understand the tests you did or the concern over the pressure in the system (you tested and it looked fine).

When I suggested operating through multiple heat/cool cycles to determine if the system really had a problem, I was referring to bringing the system up to operating temperature (you can run it for 15 minutes or 15 hours, it does not matter) and then allowing it to completely cool down. Refill the degas tank to the correct cold fluid level and repeat. It will take several days to know whether the system becomes stable because it will not cool quickly.

Do not take off the pressure cap when the system is "somewhat cooled". It needs to completely cool to draw in the needed coolant. The system is temperature driven so operating above or below 2000 rpm should not matter. At what point in all this did you notice the pint or so of coolant disappear from the overflow tank?

Did you monitor engine coolant temperature during these tests?

CaboJohn
 
Hi CoboJohn,

I have run through the cycle many times, bringing the temp to 170 degrees, letting it cool off... I still find that everything is fine until I put a strong load on the engine. (4000+ or WOT). I'm in contact with PMC
 
Hi CoboJohn,

I have run through the cycle many times, bringing the temp to 170 degrees, letting it cool off... I still find that everything is fine until I put a strong load on the engine. (3500RPM+ or WOT) then I lose a pint or so in short time. No water in oil, none that I can see in the bilge, and can't really tell with the exhaust, but that seems to be the only possibility. I'm in contact with PCM hoping to find the correct adaptor for the Degas Bottle to test pressure above 10 PSI. Initially they said the 35mm Volvo adaptor would work, but it was slightly too large and wouldn't thread. With the pressure test, hopefully I'll be able to see if it is the heat exchanger or the Head(s) without tearing the engine apart. Supposedly, this was a new tall block in 2019. Very frustrating.
 
Did PCM ever get you a better answer on the adapter? 35mm seems a bit small...did you measure the threads on the degas bottle you have?
 
Hi Makomark,

Sadly, after I told them that the Volvo adapter was too large and would not fit, they haven't gotten back to me even though I have been sending a follow-up email a day for about 4 days. I also reached out to Crusader, but I'm not sure that Contact link is still active. All we need is a correct thread size and we can put a cap on the Degas bottle and pressurize from let's say the 3/8" sensor port. Of course, the alternative is removing the Degas bottle and corking up the houses that to it. That is what my Marine Mechanic does, but it doesn't seem like we should have to do that.

I might have misread the info on the Pressure Kit I got from Harbor Freight. I see that a 1998 Volvo Adaptor is female 47 X 3 mm threads.
 
that's one of the drawbacks to searching for an adapter...the 'applicable makes' information is usually short on details, especially if they have been around a while...

FWIW, PCM bought Crusader a while back...
 
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