Cam Seals Issue (1988 3.7L Mercrusier)

[dolfan1710]

So I uncovered my boat Sunday and found a puddle of antifreeze under the motor that looks to be coming out the weep hole. I see this all over the place as it seems to be one of the most shared 3.7L 165HP Mercruiser topics on the internet. I'm nervous about attempting the job on my own as I have never done anything of this magnitude (biggest jobs I've done are push rod inspection and under drive pulley installation on an 01 Z28). Before I jump to conclusions I's like to start the boat and run it for a little while as it's been sitting since last August without being run once. It was winterized in October. My plan is to fill the coolant with 50/50 and take it out once and see what's coming out of the weep hole after running it for a while. I got an estimate on replacing the cam and it's expensive as it's a labor intensive job, although I hear mine can be done from within the boat. I have a few questions:

1. Is it dangerous to take it out? The coolant is dripping not pouring out.
2. Can I try the coolant repair liquid? It may end up being a waste but seems cheap enough to try if it's safe.
3. Should I run it and monitor the temperature and check the oil to make sure there are no signs of coolant on the dip stick? Although I forget but I think my temp gauge is broken.
4. Would the cam need replacing or could the 2 seals I keep reading about be enough?

My boat is 30 years old but we really enjoy having it and I don't believe I can get a boat that's in as good of shape as mine for the price of the cam replacement. Can I run it and get the replacement done when the mechanic is less busy?

 

[Bt Doctur]

if its leaking it should be fixed the right way or you can lose the coolant and overheat.Thats the second thing these motors really hate. most times the cam is Speedi-Sleeved to restore it to factory size and new seals installed.

 

[Scott Danforth]

as much as a 10 degree overheat will spit the head gasket. do the cam seal and speedy sleeve now.

its really an easy job.

 

[dolfan1710]

Thanks guys! So I attached muffs, filled it up with antifreeze and ran it for awhile. Tough to start but ran well once I got it going. It didn’t drip at all when running. When I killed it I can barely see it in the weep hole. I’ll check it in the morning but will likely get it fixed. What’s a fair price for the job? Is there any risk in tuning it as long as I know there’s antifreeze in there? Does it need a cam or would seals and a speedy sleeve be enough?

 

[dolfan1710]

Oh one more question my water temp gauge it busted. Does anyone know where the sensor is and how hard is it to fix?

 

[dolfan1710]

Hi guys I've been looking all over and I can't find a picture of where the water temp gauge sender is located. My temp gauge is busted and it sounds very important to be able to monitor this.

 

[nola mike]

Sender is on the bottom of the exhaust manifold

 

[dolfan1710]

Thanks! So at the advice of my mechanic I filled up the coolant system and ran the boat twice. Their are no signs of a coolant leak near the weep hole. I wonder if the seals are going but not gone yet.

 

[nola mike]

Did you pressure test the system? That should have been their advice

 

[dolfan1710]

No, but the test seems simple enough. Is it a tool I can rent from autozone? Is 14lbs. OK for this cooling system? Also, can I be sure it will seep through the weep hole and not into the oil? Would the antifreeze be noticeable on the dipstick?

 

[dolfan1710]

Sender is on the bottom of the exhaust manifold

Thanks! So the problem is my water temperature gauge is broken. This is the sender for that? Has anyone ever replaced one? Is it an easy plug and play or does anything special need to be done.

Sorry I'm asking so many questions. This is my 3rd year with this now 30 year old boat and my family really enjoys it. I just want to be able to safely squeeze a few more years out of it before I consider moving on from it.

 

[nola mike]

No, but the test seems simple enough. Is it a tool I can rent from autozone? Is 14lbs. OK for this cooling system? Also, can I be sure it will seep through the weep hole and not into the oil? Would the antifreeze be noticeable on the dipstick?

Test is done with the system empty. Yes you can rent it from AZ or wherever. If you don't see a leak, you might just keep an eye on the level for a while. Obviously it would be better to do the test, but...

 

[nola mike]

Thanks! So the problem is my water temperature gauge is broken. This is the sender for that? Has anyone ever replaced one? Is it an easy plug and play or does anything special need to be done.

How do you know the gauge is broken? Sender just screws into the manifold.

 

[dolfan1710]

How do you know the gauge is broken? Sender just screws into the manifold.

It doesn't register when the boat is running. Found out I need to empty the coolant to replace it :=( I just filled it 2 days ago). Is the coolant plug in the area?

I am gonna tap the gauge first, maybe it's broken on that end. Maybe try cleaning the wires. I guess there is a way to test it by holding the wire to the block with a screwdriver, turning the ignition on and seeing if the gauge jumps. Potential coolant leak + no temp = big potential trouble.

 

[nola mike]

OK, so you don't know if it's the gauge, sender, or wiring. Check the gauge as you said by grounding it. The resistance of the sender can be checked with the leads disconnected. I don't remember the exact values, it's somewhere in the 50-250 ohm range depending on temp IIRC.

And yeah, that gauge isn't something I'd wait on.

 

[dolfan1710]

OK, so you don't know if it's the gauge, sender, or wiring. Check the gauge as you said by grounding it. The resistance of the sender can be checked with the leads disconnected. I don't remember the exact values, it's somewhere in the 50-250 ohm range depending on temp IIRC.

And yeah, that gauge isn't something I'd wait on.

Thanks! I'll check it out after work.

 

[dolfan1710]

Got it, it’s the sender as I got the gauge to jump when grounding the wire. How do I replace it without getting coolant all over the damn place. Even if I remove the drain plug coolant will go everywhere. Is it inevitable or is there a trick?