Coolant leak after TB/WP replacement

I replaced my timing belt about 500miles or so ago. The whole thing went pretty smooth. After I finished I keep noticing the smell of coolant. When I look under the truck, the only place that looks like it could be coming from is the bottom of the middle timing belt cover just under the crank pully. So yesterday I pulled everything back apart except I did Not remove the water pump. I checked that all the bolts were torqued properly. I couldn't see anywhere that was obviously leaking coolant. Well this morning I took it on its first trip and STIll, coolant coming from the same place.

what am I missing? I obviously cant see the water pump while the engine is running. What's the trick to tracking down this leak?

When I did the water pump initially, I cleaned everything well and used a new gasket from the Aisin kit.

I think the leak is worse now that I went back and tightened everything up.

 

I have a little recent experience here

it is very, very easy to pinch or slightly tear the two O-rings

sounds like you were pretty conscientious about things and paid attention, but those things are easy to do in fact, the smaller one you can't even see because it is totally blocked off as you install the pump

You may be able to see the small one if you take off the engine nameplate I'm not sure. I would hate for you to take it all the way down again and take off the water pump for it not to be that small o-ring

When I tore that small O-ring, it was leaking where yours is but also running down The top of the engine and then pouring down the back Near the front of the transmission

For a slower leak I could see where it might only come down at that middle timing belt cover


Some others might have good ideas. Or a good idea of how you can see that one. If you can see it then a pressure test would probably help confirm.

 

I'm 95% positive its not the O-rings. I can barley see them and the top of the motor is dry.

 

Maybe I'm missing something, but I don't believe there are other places for it to leak and come out of that middle tb cover other than the water pump gasket or that small o-ring

I could never see water on my engine either

 

Note that many times, you cannot see cooling system leaks until things are under pressure. I’ve seen this dozens of times in my lifetime with radiators and associated hoses, where a pinhole leak wouldn’t rear its ugly head ‘til you hit 1,500+ RPM with the belt installed.

If I were you, I’d want to run things with timing cover off, and have a buddy step on the gas while I watch the front of the engine.

 

Well, just to follow up. I did as suggested and removed the timing covers and ran it. The leak still wasn't obvious but I could barley see it getting a little damp from the water pump housing. So this past weekend I did it one last time. I replaced both o-rings and a new WP gasket. I was very meticulous about cleaning the WP gasket surface. I even prayed about it this time when I put it back together. It must have worked because we're going on 4 days with no leak now!!!

Now I have a P0138 code pop up afterwards that I have to figure out.

 

Glad you got it resolved. If you torqued down the water pump correctly, then I would be willing to bet it wasn't that gasket since it sounds like you cleaned the surfaces thoroughly the first time. My money is on that small O-ring. Just my humble opinion since it is impossible to see and confirm that it is not pinched

 

Downstream O2 sensor, bank 1, passenger side. Basically the O2 sensor right after your cat is showing a voltage fault, high voltage, i.e. the sensor is likely bad and has an internal short. This can be easy to test in certain situations.

I went to Denso's website @ www.densoautoparts.com to look up your truck. It would appear both your upstream and downstream sensors are identical part#, and Denso is the OEM manufacturer. A quick sanity-check test check you could do: Swap the downstream sensors, then clear the codes. If the code follows, i.e. the truck starts throwing P0158 for bank 2 sensor 2, you know the downstream sensor you moved over is bad, and you'll need to replace.

I do recommend replacing upstream/downstream in pairs, or better yet just replace all 4, but if money is tight, I get it. Here are the part numbers you'll need to order. DO NOT order your auto parts from scAmazon or fleaBay, knockoff/counterfeit risks are absurdly high. Order thru Summit Racing or RockAuto instead.

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