Where is this coolant coming from? I noticed it after a 100 mile highway ride. I did another one shortly after and didn't seem to notice any additional buildup. The coolant reservoir seems to slowly fill, I haven't had it fill to the point that it overflows, I just occasionally suck out the excess and put it in the radiator. After the highway trips the radiator is low maybe a quarter gallon, some of that is in the reservoir, some is missing.

The filling reservoir has been happening for a while but seems to be a bit worse now. About a month ago I was in traffic and due to a bad fan clutch, it got hot, not into the red but close before I noticed it and immediately shut it down. I was of course worried about the head gasket, I have been checking my oil religiously since then, making sure coolant hasn't mixed. Oil looks fine.

Is it a head gasket? Where is that coolant spray coming from? The rad cap was steaming a bit when it overheated, maybe some of that spray is just from then and I didn't notice it until after the highway trip when I was missing a concerning amount of coolant?

If it is a head gasket, am I fine to run it, just top off coolant and check the oil regularly? I don't have the time to replace it right now. Should I check the coolant for exhaust gas with some of those strips or whatever they are? See if I just have exhaust pressure filling the reservoir?

Any ideas are greatly appreciated!









Also, any good ideas on how to remove all the greasy slime on the block? Any reason I need to remove it? I have Fluid Film coated the whole underside of the truck and don't really want to have all of that get washed off with engine degreaser until next summer.

Thanks for your help!
Got the truck last winter, spent the summer fixing all of the deferred maintenance. I'm still trying to work out kinks.

 

Could it be a pin hole leak in your radiator core or tank spraying when there's sufficient pressure? That might also explain why the coolant in the reservoir doesn't get sucked back into the radiator when it cools down. Look for odd colored spots on your radiator or missing/bubbling paint. Those are signs of at least a potential leak.

 

pressure test the coolant system, your leak will show up.

 

Sounds like the radiator. Either it's got a pin hole like nv said, or it could be rusted on the inside and clogged not allowing it to run through and siphoning back to the reservoir.

 

Thanks for the tips guys. Borrowed a pressure tester from orileys today, wasn't able to see anything obvious. I lost pressure fast but I think a lot of it was lost around the cap, maybe it wasn't sealing right. I'm going to clean up the dried coolant, I'll be doing that Highway trip again this weekend and right when I get home I'll check for wetness or any obvious signs of were it's coming from. I'm also going to leave the heater control on full cold to make sure that it's not the heater core.

Is it definitely not a head gasket problem? No oil in coolant, no white steam out the exhaust, runs fine. Only seems to lose coolant quickly when on an extended Highway drive.

Thanks for the help!

 

A reservoir overfilling normlly indicates a flow and or overheating problem. However a combustion leak into the cooling system can also cause this.

Verify any leaks and make sure the pressure cap is good. Verify the time it takes the engine to warm up to operating temperature. Verify the system is pressurising. After warm up and then several minutes later the system should pressuize, radiator hoses should be "hard" to squeeze. Upon reaching operating temperature both upper and lower radiator hoses should be hot.

If this issue is only occurring during these 100 mile highway trips then this likely points to a flow problem at high RPMs.
-Cooling system blockage/restrictions...?
-Coolant Pump performance..?

 

So I cleaned off any dried coolant, topped off the radiator, and went on that 100 mile Highway trip again this weekend. As soon as I arrived I popped the hood, coolant was bubbling from the radiator cap and had sprayed on the underside of the hood and ran down to the fan where some was slung around. It seemed like it had happened towards the end of the trip, didn't lose much coolant. Temp gage was just under half the whole time. Overflow was just slightly over the full mark. Could it just be a bad radiator cap? I replaced it a few months ago with one of those types with the red lever you can pull to make sure it's depressurized. Maybe during that slight overheating event the cap was damaged? I'm heading back later today, I think I'll get a new cap, top everything off again, clean it up, and see how it does on the return trip.

Before I left I drove around a bit, then checked everything. I did notice that there was a bit of coolant on the cap that I thought I had cleaned off. It would make sense. It leaking right there would let it flow directly onto the fan, spraying it around like it was when I first had the issue.

Thanks for the help so far, I hope it's as simple as a new cap. Maybe I'll get an oem one once I get back. Are they any better than the ones that orileys sells?

Got one of those freeze and boil point coolant testers. Looks like I'm just under a 50% mix if those are accurate. Could that be causing an issue? Wouldn't the temp gage read above half if the coolant was boiling? I'm not sure what the temp are in relation to the gage.

 

I recommend an OEM spec pressure cap. The ones with the silly release lever are of poor quality... and I just hate them haha.

 

Yeah, maybe the stupid lever has lead to a failure. I'll get an oem one and see if problem is solved. Thanks.

 

Are you sure that your new rad cap is on all the way? Last time I messed with one of those safety release ones I had to hold up the safety lever to get it to turn the last bit and seal properly. It should fit pretty snug on the radiator. Check out the rubber seal to make sure it wasn't pinched or cut.

 

Yeah, I have to lift the lever to screw it on all the way. I'll double check it in the morning and inspect the rubber more closely. The pressure tester was leaking from around where it screwed on. Maybe there is more too it? The cap was leaking coolant from around where the lever pivots on the cap. The tester was leaking somewhere around where it sealed. Could it be a small crack in the plastic on the radiator spout? I'll look real close at that in the morning too.

 

So I replaced the cap, drove home, no coolant spray or loss. The overflow had filled up some. I let it sit for a while and removed the cap, there was still a bit of pressure so I suspect that if I had left it the coolant in the overflow would have been sucked back in as it cooled more.

So looks like that was the main issue. Bad cap. Surprisingly simple fix. I'm going to keep an eye on the overflow and make sure that it gets pulled back in like it is supposed to next time.

Thanks for the help!