Weird coolant leak?!?!

[93TwotoneXLT]

I recently replaced the lower intake gasket along with all of the associated gaskets to do the repair. I am finding what I think is coolant on the lower intake valley(between the fuel injector and the intake itself) above the #2 cylinder. I cannot figure out where it is coming from. If I soak it up and let the truck idle for a while and drive it around it will not reappear when I check it again. If I don't check it for a couple of days then it will be there again. I should add that all of the hoses appear to be dry when I check them cold and hot. Anyone have any idea what may be going on? Thanks for any ideas.

 

[BrooklynBay]

Did you check all of the bolts in that area to see if any of them are loose? Maybe there is a pin hole in a nearby cooling system hose? A cooling system pressure tester would come in handy for troubleshooting this.

 

[93TwotoneXLT]

Brooklyn, I have been meaning to get a pressure tester, probably will tomorrow. It is weird though. All of the hoses and connections appear to be dry anytime I check them. Heck, I can't even think of a coolant hose that runs close enough to that area to dump coolant in there. Your bolt explanation is interesting. Think that it is possible for one of the lower intake bolts to have backed off a little since I replaced the gasket, therefore causing the leak? As a note, I did torque all of the bolts in sequence when re-installing the lower intake manifold. Man, you must be a night owl like me.

 

[BrooklynBay]

I once had a similar problem on my 88. The head of one of those bolts cracked off. I had a tough time grabbing the existing stud, but I did get it out. I replaced the bolt, and that was all which was necessary.

 

[93TwotoneXLT]

I hope not. I am going to take a look at it later and see if I can find any coolant traces around any of the bolts. I'll update when I know what is happening.

 

[93TwotoneXLT]

Update: After looking for a while I ruled out a leaking coolant line, as none of the heater hoses or main hoses goes anywhere near the intake at the #2 cylinder. Plus if one of the lines did have a pinhole in it then I would have traces of coolant all over that general area of the engine. Deciding to start from the bottom up, I pulled the spark plugs and checked for signs of coolant getting into the cylinders and all plugs were dry as a bone and looked great, no oil in the coolant/coolant in the oil. I then checked the lower intake manifold bolts with my torque wrench and none of them were loose, and all of the bolts are intact and in good shape. So now I moved on to the upper manifold bolts and find that the four central bolts are all very loose, and have actually backed off since I replaced the lower manifold gasket and all that. I re-torqued the bolts and so far so good, and the light pinging I was getting in OD on the highway while accelerating is gone for now. Hopefully this took care of the issue, and will stop the leaking coollant. At first I couldn't believe that the bolts had backed off like that, but then I remembered when I had new tires put on the truck awhile back I checked the bolts after a couple of days and a few of them had also backed off on their own, and I know that can happen, so maybe that isn't too abnormal. Thanks for the suggestions Brooklyn.

Moral of the story, if you take the manifolds off to replace something make sure that you check and re-torque the bolts after a few days.

 

[BrooklynBay]

Try locktite too.

 

[93TwotoneXLT]

Thanks Brooklyn. Yeah, I thought of that and I am going to check them after a week. If they have backed off again at all I am going to use loctite on the nuts. Still don't know how loose upper manifold bolts would cause a small coolant leak, but the bolts that had backed off were right above where the coolant was puddling on the intake and it hasn't leaked again yet. Hopefully the problem is fixed.

 

[93TwotoneXLT]

Well, it wasn't the manifold bolts, puddle showed back up after a couple days of driving. I think that I have got it licked though. I think that the upper radiator hose was the culprit. I looked at it again in bright daylight and found traces of coolant on the temp sensor, wire bundle around it, and what looked like a possible trail from the front of the intake to the back. So, to check this possibility I loosened the hose clamp for the upper hose and voila, the coolant was seeping out and went exactly where I was finding the puddles of coolant. The hose is new and the clamp was tight, but I had the clamp right on the edge of where the hose goes over the tube for the thermostat housing. I moved the clamp up and tightened her down real good so we will see if takes care of the issue. Just thought I would share if anyone runs into the same problem.

 

[DaytonCobra]

This is very interesting. I am running into the exact same problem except the coolant on mine is puddling up around the number 1 fuel injector. I will try the hose!