Logo
FULL SITE MENU

Coolant loss after T-Stat replacement 5.0 M/C

R

rick3452

Regular Contributor
For over a week of dailyuse I am still adding maybe 2 quarts of coolant every day and the overfill res is empty everymorning. Nothing in the bildge no visible leaks at all. Its a half system so I cant figure out where is this going. I tested to bottle last night as I pull the return hose off at the cap and the bottle lost nothing. Thanks gor any ideas...
rick
 
If your recovery system is working, there's only two places this coolant be going in a half system.

1.... an internal leak within the heat exchanger .......... I.E., leaking coolant into the sea water side.
2.... head gasket failure.

If a head gasket failure was causing this, you'd likely see over-pressure at the H/E and recovery reservoir.
Since you did not see any coolant in the bilge from over-flow, my bet is an internal H/E leak.
I'd begin by having the H/E pressure tested.



.
 
Rick, In the future do not start a new thread on the same topic. We loose continuity of what has been offered. Your problem will most likely be served best by the basics. As Ricardo has offered, a Head Gasket is a possible cause for the lose of coolant. A Compression test followed if needed of a Leak Down test will rule out a multitude of expensive causes. How does the oil look? Excessive steam in the exhaust? Problems like this need to be diagnosed carefully to avoid wallet failure. Al W.
 
Al, My apology, and will not repost a same topic in the future.....

There is no steam in exhaust and oil is perfect. I did (just as a thought) drain the water from the blue petcocks on the bottom of the manifolds thinking that I might see signs of coolant, nothing at all. If I take te ends off the H/E are the gaskets reusable?

Thanks again.....
Rick
 
If the end gaskets are still soft and pliable you can, but do risk a leak. That said, I'll be waiting to hear your Compression test results.
 
Simple user friendly test:
Remove the pencil anode, and drain the sea water from the H/E.
(the pencil anode typically doubles as a sea water side drain port)

Make sure that the E/G level is up to snuff.
Use the radiator pressure testing cap, and pressurize the system.
Since this is likely a slow leak, give it some time while remaining under pressure.

If you can create a leak from the E/G side into the sea water side, you should be able to see E/G coming from the pencil anode port.


Edit:
Rick, if you want to reuse the end cap gaskets, mark the H/E shell, the gasket and the end cap as to index them and keep them on the same ends.
Perhaps make one mark on each for the Port side shell, gasket and end cap....., and perhaps two marks each for the Stbd side.
If you can re-index the gaskets, they'll likely seal again.

Or.... purchase new gaskets.


.
 
Last edited:
Ok. I think I figured out that it is the H/E , the bottle drained again last evening, added more to the bottle to a COLD engine, two hrs later it was down quite a bit. This time I lowered boat, started it and ran back to watch the exhaust,
There goes the antifreze!! after maybe 15 sec. it stopped. I called local HE repair shop and explained what ws happening and he feels that the HE is the problem. $175 to $220, to clean and repair. Off to the shop tommorow!
I will report results, and thanks again for your help.

PS eng has 835 hrs. and runs perfectly
 
Whoah.... if you were able to see the exhaust water change color, your leak was much worse than what I was expecting to hear of.
Good that you found it, and are having it repaired.

Keep up on your H/E pencil anodes. Sometimes this means two or three per season.


.
 
Dropped if off today, and while I was there they pulled the end caps off the HE. We found 3 pcs of my impeller (bravo 3) One good size piece was jammed in one of the exit tubes the guy said that that would create back-pressure, so in a couple of days I should get it back.
Ps I did the new impeller job and T- Stat same time. Thats when this problem started.

Ricardo, I can not find the pencil anode anywhere???????
 
UPDATE:

I spoke with shop today........ He said there were aprox 5 leaks he said he may have to block off those leaks which could effect the cooling capacity, or maybe replace the HE. I guess I have to decide when I go there in the am.
My question is, will blocking off 5 tubes be a problem? The boat has never been used for ski-ing etc . and always runs 160 deg.
Thanks for your input before I make the decision....
Rick
 
Ok, Got H/E back from the shop yesterday, put it in, filled according to "Boat-Techs" Mercruiser instrutions, fired it up, took it out and all is well. This morning coolant is still there.

Thanks to all...

Rick

ps: There is NO pencil anode on my H/E anywhere??
 
Back
Top