Water leak on passenger side of engine after alternator replacement
 

Hi All,

So this week I had to do an alternator replacement on my 4.8i which all that seems to have worked out except:

1. There seems to be a squeak coming from the belt?

and

2. I have water/coolant leaking from the passenger side of the engine which is enough to cause steam to also rise on that side (not to mention it going through a couple of gallons of water thus far).

I have no idea where the leak is coming from on the passenger side of the engine - only know that it is reaching something hot enough to cause steam (whether it is from the heat of the fluid itself on these cooler fall days or it is hitting the exhaust manifold/engine somehow.

We were obviously focused on the driver side of the engine where the alternator is, so it's completely puzzling that I have coolant dripping and steam rising on the passenger side of the engine.

Any ideas?

Thanks in advanced!

On the e53 very common to leak from the sensor on the lower hose sensor.

I think on e70 they moved that sensor into the coolant pump.

You didn't say which motor.

N62 i think that might still have mechanical pump and sensor in the lower radiator hose. Very common leak. Just needs a new o-ring if that's the case. I just wrapped mine in Teflon tape meant to be temporary turned out to be permanent.

Sorry, N62 (4.8i)

Water leak on passenger side of engine after alternator replacement
 

https://uploads.tapatalk-cdn.com/202...a753744298.jpg
This is the number one culprit.

https://uploads.tapatalk-cdn.com/202...8f0cd33699.jpg
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https://uploads.tapatalk-cdn.com/202...a93eaef28f.jpg

Water leak on passenger side of engine after alternator replacement
 

I made a temporary plug from PT and rubber glove to put in the sensor hole.

Wrapped o-ring in Teflon.

This happened 2am before a 4 hr drive home for family gathering that day.

The tire change was on the way home. I think my original departure was 1 for 5 i left after 2 arrived after 7am.

In one photo you can see an additional sensor i grabbed out of the motor i was working on. Turned out its o-ring was just as D-shaped as mine so i just patched mine.

I ran out and got some UV dye and put it in the tank with some water.

I haven't noted anything around the temperature sensor - the steam I would see does come from that side but the dye was showing up near the throttle body. I didn't run it long enough for the tank to empty itself (yet) but I'm thinking it's the vent pipe that branches off to each upper head.

Should there be something else I am looking for in that area, like the transfer pipe weep hole? - hopefully not that :(

Do you have a good UV light to help track the dye? It will show up for sure at the rate of loss unless it's burning up through head gasket.

You can use low temp pressure test on coolant system. Get it to drop while not hot or driving.

Puddle?


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So me and a friend both looked around with the UV light and dye while running at idle. What we see is the dyed coolant/water running down the valley pan but nothing from the weep hole so I think the transfer pipe is fine.

The only thing we can think of is the vent pipe that goes to the valve heads and return coolant hose. When I would run it at 2000RPM for a few minutes then go look, I could see a drip drip drip just below the throttle body/intake.

What we are wondering also is why the return hose isn't getting hard with pressure despite being able to feel coolant and heat.

It's not spraying anything... but it is not pressurizing and it will empty out a gallon of water over about a 5 mile run (measured by the amount of distance it took for me to run from home to the autoparts store and back before the coolant low message would pop up).

I would have to describe that it would be of similar result as this post...
https://xoutpost.com/1132793-post5.html

Fiber optic camera to look under the intake?