I have a 1991 f150 with a 5.8L. The other day it started squirting coolant from where the thermostat bolts to the engine. It appears to be coming from the head portion just to the left of that bolt. Any information or suggestions?

 

Are you sure its not coming from the tube just above that point, the tubes the red arrows point to rust through, you might be seeing the result of a pin hole shooting straight down. The bottom of the tubes rust through before any other point.



Small tube can and will too and doesn't look good in your picture, but the larger tube tends to rust through first.

If not how about reposting your picture with an arrow pointing to where you believe it leaks, same way I did it. If you're not sure how to do so, right click on the picture and click "copy" open then paste image into "paint". Use pencil or brush in paint and a contrasting color of your choice to draw an arrow. Save the picture to known location in your computer, then upload same as you did the first time. Once uploaded you can delete the file, desktop for example is a handy location.

 

Clean it up , pressurize the system with a coolung system pressure tester and see where it leaks. Im not sure if autozone has them in their loaner tool program or not.

 

I know Oreilly's does.

 

Looks like it's leaking pretty good, probably won't need a pressure tester. Warm it up, hose off the coolant with water, blow it down with air, and watch for the leak. I say warm it up because if your radiator cap is working right then it'll let the system pressurize on it's own.

I agree with the above posters... that tube likes to spring a leak so it's worth another look.

 

The leak comes from that little area and when I squeezed on the upper radiator hose I could see it squirt out. I'm not sure if there is a gasket there that failed or if it is the head itself that is cracked. I'll definitely check out those little tubes too.

 

If it's leaking there, then it's the intake gasket that had failed. Next step would be to buy new bolts since that one where the arrow points is gonna be corroded.

Its not a hard job to tackle, but it's gotta be fixed. Let us know what you plan? If you do it yourself, we can help you out.

 

If it's squirtin from that exact area then it looks like you'll be replacing the intake manifold gasket. Doubt the head's cracked, probably just the gasket got tired of holding back the coolant after all these years.

 

I plan to do it myself. Is it normal for there to be coolant there?

 

Sure is. The water pump takes water from the bottom of the radiator, pushes it up thru the block, then into the heads, and then from both heads it all goes into the intake manifold so it can hit the thermostat on the way back to the radiator.

 

That could also cause a vacuum leak, which can cause a lopey idle, correct?

 

It's possible. Seeing as how that gasket is already failing, I wouldn't be surprised at all to find it leaking around the intake ports too.

 

While I'm in the engine, is there anything else I should replace? Do you have any tips or tricks?

 

Sure. You might want to find an EGR tube before you take the manifold off, since they are thin and like to break. Unless you don't have smog checks in your state and don't care about EGR.

Don't cheap out on the gaskets either. Get GOOD ones from a respectable brand. Now me personally, I'd probably put a LIGHT coat of Permatex #2 non-hardening sealer on each side of the gaskets, but that's my preference and I'm sure if you took a poll you'd get answers all over the place.

 

How do you feel about fel-pro? I heard about putting on a high temp silicone on the front and back to prevent oil leaks.