Help identifying source of coolant leak

[RussAdams]

Hi everybody.

Well now that I have my driveshaft fixed (earlier topic) I'm now experiencing a coolant leak. Where would coolant be coming from on the front drivers side of the engine? I don't see any coolant pipes here, so I'm puzzled.

You can see the alien green puddle on the drivers side of middle in the first photo (green puddle just right of center - white looking puddle on rear left is A/C condensation drips). You really can't see much looking down from the top in the second photo. Coolant is very visible looking up from the bottom in the third photo and fourth photo. But no hoses in sight? Where's my leak coming from???

Edit: 1999 XLT 2 door extended cab 4.0L OHV 4x4 with automatic Transmission.

Thanks for any help you can give! Russ

 

[Uncle Gump]

These are known for thermostat housing leaks. Also get a good look at the vent hole on the bottom side of the water pump.

 

[Shran]

I assume this is a 4.0 engine? Those are known for timing cover seal blowouts too, in this area on both sides. Not sure of that on yours though, it looks like it might be coming from higher up.

 

[Vindictus]

those pic's look a lot like how mine looked when my thermostat hosing crack. I found it very hard to figure where it was coming from. Is what brought me back here. This place has an amazing amount of info. And the most unbelieve helpful people

 

[RussAdams]

These are known for thermostat housing leaks. Also get a good look at the vent hole on the bottom side of the water pump.

Thanks for this. I will put it top of the list when I get back next week.

 

[RussAdams]

I assume this is a 4.0 engine? Those are known for timing cover seal blowouts too, in this area on both sides. Not sure of that on yours though, it looks like it might be coming from higher up.

Sorry! Yes it is a 1999 XLT 2 door 4.0L OHV. I'll edit the original post.

Does water flow through the timing cover?

 

[RussAdams]

those pic's look a lot like how mine looked when my thermostat hosing crack. I found it very hard to figure where it was coming from. Is what brought me back here. This place has an amazing amount of info. And the most unbelieve helpful people

The thermostat housing looks good. I will double check next week! Thanks

 

[Shran]

Sorry! Yes it is a 1999 XLT 2 door 4.0L OVH. I'll edit the original post.

Does water flow through the timing cover?

yep, on both sides. goes through the timing cover to the water pump

 

[RobbieD]

The pics makes me think of when you get a pin hole leak, that doesn't leak until you stop driving, and the coolant flow stops with the cooling system hot and the pressure high. Those kinds of leaks can then start pissing out of the pin hole; they can put the coolant in other distant odd places, and that makes them tough to find. Try popping the hood after a good drive, and watch for a pissing leak.

Good luck!

 

[North Idaho 5.oh]

My personal experience with a leak anywhere near that location is the lower intake (been twice now) and from that point it’s still not a bad idea to replace thermostat and housing along with the lower intake gasket.
Just hope it’s not a head gasket failure

 

[RussAdams]

The pics makes me think of when you get a pin hole leak ... tough to find. Try popping the hood after a good drive, and watch for a pissing leak.

Good luck!

Thanks RobbieD!

 

[RussAdams]

My personal experience with a leak anywhere near that location is the lower intake (been twice now) and from that point it’s still not a bad idea to replace thermostat and housing along with the lower intake gasket.
Just hope it’s not a head gasket failure

Thanks North Idaho!

Wow. So coolant flows through the lower intake manifold too? Yikes.

Looks like I've got my work cut out for me on this.

I'll add that to my list.

Any suggestions on how to check it?

 

[RussAdams]

Update on June 21, 2024:

I removed and replaced the gasket for the timing cover. That gasket was definitely leaking. While I was there I also replaced the crank pulley (harmonic balancer) and the water pump. I ended up using a 1/4 inch ratchet extension (six inch) and a gear puller and the crank pulley came right off.

This was a very long job. Took me several days to get it all done. Bummer getting older.

Thanks for everyone's help and suggestions!

 

[RussAdams]

June 21, 2024 update continued:

Unfortunately this did not completely solve my coolant leak problem.

When I turn on my a/c I get a leak from the front of the engine. I have the front up on jack stands, and the fluid seems to be coming from somewhere in front of the starter motor, on the driver's side. This photo: the rear of the truck is on the left, the front is on the right. You can see coolant following the electrical line in front of the starter motor, travelling from the front (right) towards the back (left).

I have inspected all around the timing cover gasket and there is no sign of a leak. This is a driver's side photo.

Any suggestions where to look now?

Thanks! Russ

 

[RussAdams]

Update July 17 2024:

I found my leak. It was from a blown intake manifold gasket.

Here's the hint photo. You can see the orange gasket seal on the left, and the uv activated green above it to the right.

I initially thought it might be the head gasket, but once I removed the intake I could see it was leaking from the intake gasket not the head gasket.

Closeup of the blown intake manifold gasket

Lucky that it was just a gasket and not the manifold itself or a warped head!

I pulled both heads and will replace head gaskets as well as all intake gaskets while I'm here. I bought an EngineTech gasket set.

The pushrods were pretty worn, so I'm going to replace them and lifters while I have the engine apart. I can see cross hash marks on the inside of the cylinder walls, so this engine has definitely been rebuilt at some point. The valves all look good too. The EngineTech gasket set included valve seals so "while it's apart"...

Thanks for everyone's support!

Russ

Unhappy to get the leak, but happy to see good signs of engine interior, top end at least.