Leak Diagnostics

[dclassic]

Hello All! I could use some help with a frustrating problem. My 96 454 Mag has sprung a leak and I am having a heck of a time finding the source. I hate having to clean the bilge after every outing and I am sure the leak is costing me at least .01 Mph on top :D . It is leaking coolant water somewhere near the front of the motor and belts. I get a mist of water thrown off the belts in the hull but I can't find the source. I checked and torqued all the hose clamps and fittings, no water from the water pump or weephole, no visible damage or leaks in the hoses, raw water pump is dry also?! The harder the boat is run, the more water in the bilge. I have been all over the motor, on top, in front, under, sides and back, and yet I can find no source of leak. I seem to get a good mist on the oil cooler from the belts on the front left of the motor, but I also have a nice mist on the hull all around the belts:mad: .

Any help would be appreciated as I am about to pull the motor and just start replacing everything that holds water. Unfortunately that will get pricey and my wife may further question my sanity. On a side note, has anyone tried to install the nice billet trim tanks? What is the best hyd trim fluid and bleeding method? Thanks in advance and happy :boat: .

[mrfixxall]

I would start with tightening all the hose clamps..I would also check the oil cooler to see if it ever froze,it dont take much to crack them when thay freeze..Ware i live in the midwest people forget to pull the plug it the oil cooler and it freezes..you may want to take off the hoses going to the risers and connect them together with a piece of 3/4 or 1' pipe then remove the intake hose at the transm and shove your garden hose in the end and clamp it with a hose clamp around the brass part of the hose (i use a 3/4'' pipe union and screw it to the end of the garden hose and clamp around it) ..Then i turn the garden hose on just enuff to pressurize the cooling system and start lookin for your drips and you should find it with this methid.....

good luck!!!!!

[Lenny]

Raw water crank mounted pump "might" be a source at higher RPMS...and not at lower ones. (That is if you have one) :)

[Ted Guldemond]

I had something similar a few years back in my cruiser ( 454 mercs). It turned out to be the circulating pump. Just a fine mist of antifreeze thrown off the the back of the pulley hub. There was no sign of leakage from the weeper hole, as it only leaked when running. Try loosening the belt on the the circ. pump and see if there is any side to side play in the shaft.

[MOP]

I think Ted hit it on the nail, when the seal is just starting to go it only leaks out the weep hole while running. There is a lot of pressure in the system at running RPM's, you may be able to get it to leak at the dock by bringing it up to about 2500.

Phil

[mrfixxall]

i also agree with len,ted,and mop..But i think the key to finding a leak is without heating the engine up,it swells every thing when it heats up..i have found many,many,many leaks with the garden hose method..if the water pump was leaking i would think you would see water deposits on the pullys,hoses etc...

[Donzigo]

Ted - MOP, I was just going to say exactly what you both said. If one finds water on the inside of the pulley, after a run, it's the circulating pump. Remember that there won't be much water found; becuase, the pully naturally throws off the water as it turns.

[dclassic]

Thanks for the advice. I have felt the backside of the pully on the recirc pump and it seems to be dry. I figured that was probably the problem initially, but now I am not so sure. I willl try loosening the belt and checking for play in the shaft just to be sure. I think the idea of pressurizing the system with a garden hose will help a bunch. Sure beats crawling around the bilge with the motor running trying not to get tangled in the belts. BTW, when should one replace the cooling system hoses for preventative maint.? I have a raw water pump rebuild kit, new belts, tune up kit, and all new fluids to install. Should I change the hoses as well or is that not necessary. My nice new billet trim tank should be arriving soon also. What kind of tools do I need to check engine alignment? I am not sure if I am going to tackle that or let someone who knows a bunch more than me do it. Thanks again all.

[mrfixxall]

the hoses ???? do thay feel soft and flimsy....i have a 78 formula with 800 hr on it and the foses are still oe...if their not broke then dont fixx them...the tool you will need to check the drive aleignment looks like the pic below...

[dclassic]

I didn't know if the hoses needed changed every so often like a car, I will eave them alone as they seem fine. Where can I score an alignment tool? Are they avail from most marine dealers? Thanks again

[mrfixxall]

http://marineengineparts.com/shopsite_sc/store/html/page58.html try this place thay have them for 82.40...some dealers wont sell them and some of the cool ones will......

[mrfixxall]

The Merc one is 87.78....
Madpoodle is one of the cool ones....