lost coolant
 

I have a 496 mag ho with closed cooling system on it and noticed when I got it back from having outdrive serviced and impellar replaced that the engine coolant reservoir was almost completely empty.I have not had the boat in the water yet but have ran it off the hose for about 5 minutes.It did not get hot but unfortunatley I didnt notice if it was low before I ran it.Im going to fill it and run it to see if I loose it again and was wondering if there is a particular place to check first. I did check the oil and it is clean and no coolant in the crankcase. Also when the impellar was changed would there have been anyway coolant would have been lost there. I would assume not since that is the sea water side.

Ya, the sea water pump doesn't have anything to do with the coolant reservoir. Do a search on this topic. There is an issue with 496's leaking coolant from the heat exchanger when the boat is subject to large temp swings. Mine does it occasionally but it's only a few drops.

Where did it Go??
 

Fill Your Coolant level back to indicator mark and tighten the cap and warm the engine to operating temperature, then turn off the engine and slowly release the cap on the coolant resivroir, you should hear the pressure escaping when the cap releases. If the tank is holding pressure you probably don't have a serious leak if any, however if no pressure builds when the engine is warmed up then the pressure is escaping somewhere and coolant with it.
You can also do this test on a cold engine with a Stant or Snap-On pressure pump with the proper adaptor to screw onto the coolant tank. Take the pressure on the system up to about 14lbs. with the pump and let it sit and see if the pressure drops. If it does, you have a leak somewhere and if you see no evidence of coolant on the outside of the engine, then its leaking into the engine somewhere. when you fill this system remember to use Dex-Cool coolant full strength.
Some years of Merc 496's had coolant leaks from the rubber sealing rings under the coolant tank that seal the coolant tank to the crossover tank support. These leaks are external and should be visable and also drop to the bilge. Mercury had a recall on these for some years and even if yours does not qualify they are relativley easy and inexpensive to change if they are leaking.
good Luck, hope these points help in your missing coolant mystery.

Best Regards,
Ray @ Raylar

If all that checks out ok just keep a eye on it on your next few trips out. Just a Thought maybe the teck that changed the impeller tryed to back flush the cooling system and pulled off a wrong hose for a second or too and for got to refill the coolant tank back up. Look in the bilge area all over to see if you see any signs of old cleaned up coolant he may have have missed a spot.

When this happened to me on our previous boat it turned out that the heat exchanger was leaking internally. The pressure of the closed cooling side was pushing the water through a tiny hole and into the raw water side, therefore slowly causing the coolant level to drop. It had to be replaced (I had Mercury Product Protection so it was covered at the time).

Sometimes the head bolts can leak too. Normally outside the valve covers.

I have two head bolts leaking on my '02 HO. They are oustide of the valve covers - #2 and #4. It takes a lot of running to drop the coolant tank empty (and leaves a mess in the bilge)

Hate to hear it but I thought I was the only one. Drives me absolutely ph_cking nutz!!!

I've had the exhaust off 4 times now trying to get it to stop. Same for me 2 & 4 on port side.

Total, utter :bsflag:

What did you clean the threads in the block with?

My guess is the shop that did the service got it hot at some point and you lost some fluid when it overheated. It sure would have been nice if they would have at least topped it back off for you.

sdfever and raeburn you both have raylar heads,,,what raylar have to say about this???could it be tha heads bolts that come with the kits??,,,?raylar

What heads are you running stock ones or ???, A few things come to mind when thinking about this maybe the bolts are under torquet, Or have been over torquet and now the head bolts are streched out not doing there job, Or maybe the head gasket is weak in that area when the head gets real hot. Or maybe after A long hard run maybe the heat is expanding one of the materials used in that area like either the head to gasket area, Or the head bolt Holes Area are expanding when hot and under pressure making them leak with in combo of the bolts not tight enough with head gasket used. Mayby next time you are out playing around on the boat you should take your infa-red temp reader gun and test it at warm up and then after a long run and see how hot the bolt area gets just to see. Just some thoughts for you but i'm sure you have done that your self. Good luck with it. :party-smiley-004:

This is not the issue but I agree with you. You have to consider every possibility.

I just got mine back about a month ago ...My heads leaked and they are Raylar heads...And the leak was coming from 2 of the head bolts

You said "was"... Sounds like you fiixed it. Please share what you did.

I really don`t think I wanna tell the story on an open forum I am just way to nice of a guy....

You're just glad Paul doesn't read much of this stuff.

Why did he work on it?:party-smiley-004:

you lost me. i didn't get it...:lolhit:

are they still leaking or is there a fix,,, with 500 kits out there what gives???

I AM Here!
 

Twin-Spins:

You sound very concerned, do you have Raylar kits on your engines in your Baja, I don't recognize your screen name or your boat. If you have Raylar kits are your heads leaking?
Yes we have hundreds of Raylar heads all over the world since 2002 and I only know of a tiny few ( one or two customers)who have ever had a leak from the head. Our serial numbers on heads now number according to our book number 612 out there and thats a pretty good representation of of our product and any potential for problems as two or three heads with an issue. We don't ever claim we can always make perfect parts as no manufacturer can. We do however stand behind our product above and beyond the call of duty on warranty and even BoatingBent knows we supplied a new head for his engine even after his kit had been used for three seasons. Try buying an Edelbrock, Dart, Merlin or AFR pair of heads and going back to those manufacturers for a warranty on a cylinder head after two or three years of use! They won't even return the phone call! because the warranties of these manufacturers cover no marine high performance usage, let alone 2 or 3 years of use before a warranty claim!

SD Fever, your engine is less than one year old and if there is a problem with your head from a potential leak we will repair or replace the head as needed. It is also important to know that all the head bolts are wet, they all go into the water jacket of the 496 and if the thread sealant is not put on initially adequately, the head bolts can drip or leak coolant . As always my phone is always on and I am willing to discuss anyones 496 problems, especially on Raylar equipped 496's. I just don't want this thread to be perceived as though there is some big problem out there with Raylar cylinder heads, as I know there isn't!

Best Regards,
Ray @ Raylar

Go to your local auto parts store and buy a bottle of Irontite and add it to your coolant. This stuff will seal just about anything !!! As far as replacing a head after 3 seasons that is going waaaay beyond the call of duty!!!!!!!!! keep up the good work Ray.

I agree with you Ray, I don't believe my coolant leak is caused by the Raylar heads either, I think the re&re of the heads and resealing of the head bolts is the problem.
I'm wondering if the sealant is getting pushed off the threads as the bolt goes into the block. My most recent attempt involved cleaning the threads with brake clean and a rifle brush, blow dry with compressed air (repeated about ten times), and then applied Permatex High Performance to the threads in the block with a small screwdriver as well as to the bolt threads. I threaded the bolts slowly and let cure for two days before refilling.
After filling and running on the hose up to temp (for about 15mins), there's no leaks! Fingers crossed for water test this weekend.
My concern now is if the ARP bolts can be retorqued that many times without losing their stretch?

First, the ARP Bolts are able to be reused no problem. The factory bolts are Torque-to-yield and they claim you should not re-use them. That is actually debateable... Moving forward -

I think I've found the solution to the head bolts leaking and I'll share it with you asap. I won't have time to do it until after the holiday weekend but I will do my part to help you all out. More later.

No offense but please don't do this unless you want your coolant tank to be chit ugly... Lemme try my plan B first and I'll let you know.

3 years is pretty darn good service.

Raeburn:

I spent some serious time with SDFever going over how to remove the head bolts one at a time, drain the coolant, clean the threads in the block , clean the bolt threads, reseal with some new sealer SDFever came up with and hopefully stop these nagging little leaks. I am sure he will go over the process in detail and if we ever find its a head issue we will address that then for sure! enjoy your boat be safe and have fun!

Best Regards,
Ray @ Raylar

I would rather have a chit ugly coolant tank than real pretty anti freeze leaking from the head bolts and laying in the bilage but thats just me. good luck with your leak, Jeff

Good to know about the ARP bolts - thanks. Let us know how you make out, hope you have good results.

Thanks Ray,

I know we will find a solution to this annoyance. In the mean time I plan on enjoying the boating season. A little coolant leak won't get in my way!
I ran mine a bit today and one of the bolts started weeping a little - nothing like before, but still not 100% fixed. Curious to hear how SDfever makes out.

Well you got me on that one. Neither is good.

How'd you make out SDFever? Mine are still dripping, not as bad as before, but still annoying. I think I will wait till the fall before I make another attempt at sealing them and just run the boat for the summer, keeping a close eye on it.

Actually working on right after the 4th. No use in tearing the boat down until after. Just been busy at work and every time I start getting ready I either have to drop it or it's a nice day and I wind up running it.

It's really hard to work on a boat with my boating schedule. :drink:

have someone do it ,,,you know what needs to be done

Hey, how did you make out with the thread sealant, any luck yet?

I"ve been through a lot in the last year and a half or so. I broke one of my engines and then I bought some new stuff - heads, bottom end, and I made a bunch of changes before I got a chance to play with it.

Bottom line is it's fixed for now.

:coolcowboy: