Idles cool but overheats at speed... help?

great explanation. I didn't realize that that was the reason for the double seals on the rad cap. I didn't know that the overflow inlet or whatever you call it actually came in between the two seals. That makes sense now. And then the check valve in the cap on the over flow maintains the seal necessary for the suction needed to draw coolant back into the radiator. Now I feel dumb for not knowing that LOL. Thanks for the info dude.

 

Head gasket

 

Plugged lower 3rd or more of the radiator.

 

Alright people. I installed the new fan clutch and went for a drive. Truck sounds way different. Quieter. Which is odd since the fan seems to spin with a slight bit more resistance. But I am still overheating.

I purchased a new radiator cap and installed that. Still overheating.

As a clarification, when I mentioned that my radiator was "not plugged up" I was referring to the exterior. As in its not full of bugs and shit. I sprayed the exterior out with a hose.

So.... thoughts? This is getting old. Am I due for a new radiator? If that is the case, would anyone care to make a recommendation on what brand/model radiator would fit and be best?

At this point, before investing in a radiator should I take it to a professional to see what they say? Could a shop run a pressure test on my system to detect possible leaks at the head gasket?

One more question, since this is my daily driver, what temperatures could possibly cause damage to my engine? Should I park it?

Thanks for your input. -Justin

 

Have you looked between the Radiator and A/C Condenser to confirm there is not a ton of leaves between them?

Any bubbles appear with the engine running and looking down the radiator fill hole = head gasket issue?

It could very well be the radiator at this point.

 

I was taught that all cooling problems can be divided into two categories. Then start narrowing down further from there. (Assuming engine oil level, fan belt, collapsed radiator hose and thermostat check out.)

Vehicle runs fine at idle- A test drive reveals it overheats at speed. Indicating restricted or no coolant flow through passageways. Could also be collapsed exhaust exhaust or dragging brakes. We're dealing with the cooling system so those can be ruled out.

Vehicle runs fine at speed but overheats when stopped. (the only thing that changed is airflow)
Restricted airflow through radiator.

 

No bubbles in the radiator that I have observed. There is some grass clippings in between the radiator and the A/C condenser which I overlooked, but it doesn't look sever. I will be removing them today. I am at work right now. Will probably pull my truck in the shop and try to blow them out.

 

Oil level is fine. Due for a change but level us fine.

No collapsed hoses that I have observed while holding the throttle at 2,500 RPM.

My exhaust is fine. Relatively new cats.

Brakes are definitely not dragging.

Engine temp will climb at 2,000 rpm up over 210* but as soon as I slow down it starts to drop.

Thanks for the reply.

 

At this point, I vote for a vacuum fill.
You worked hard to get all the old out, I think you have an air pocket trapped some where and a vacuum will be the only way to get it out.

 

Get a temp gun and laser different areas of radiator. If you ever put town or city water in that radiator you made salts that are clogging tubes so you are not getting flow thru radiator.

 

I have never put anything other than antifreeze or distilled water in my radiator. I have a temp gun. How close in temp should my readings of the hoses and radiator be to the temp that the sensor is telling me? Thanks.

 

It should be a gradient from hot to cold, as you go over it if there is a much colder pocket where the rest of the width is hot still you know some of it is blocked off, you're just looking for consistency more or less from right to left as you work your way down.

 

Get a coolant bottle test strip before you piss away anymore money trying to refill the parts bazooka.

Overheating under load is a classic sign of a failed head gasket.

 

I agree, get this test done 1st, before you go any further, you can have the beginning of a bad head gasket with just a few small symptoms, one being over heating, but look ready hard in between the AC condenser foot print on the radiator side. It tends to cake up with dirt bugs leaves etc and you can’t see it unless you move the condenser because it’s between the radiator and condenser inside section

 

Probably blown on exhaust side...

My Civic blew the same way. Very hard to tell except for the fact it's running hot without any other culprits.

 

I had an overheat once that defied all my attempts at trouble-shooting. Turned out, at speed the suction hose was collapsing and blocking coolant flow. New rad hose fixed it. Normally rad hose collapse is from a defective pressure cap. Mine was just a bad hose.

http://knowhow.napaonline.com/radiator-hose-collapse-diagnose-fix/

 

The easiest way to urge air is with a flush/refill T. You can get them at Walmart for a few bucks. It goes in the highest heater hose and let's you flush and fill without needing to park on a slope. Just pop the cap and any air will be able to escape as unless you're car is upside-down, it's at the high point.

You already found its not your fan clutch, but it wasnt going to be that anyway. At speed your fan does nothing but basically freewheel. A spiNing fan can't spin fast enough to pull in more air than is already being rammed in there unless it's attached to a jet engine. That's like expecting a river to flood because you spit in it.

You've checked your thermostat.

You've checked the radiator cap.

You're left with only a few options. Either a head/gasket problem, running lean, or an obstruction.

You've checked your hoses and found no soft spots?

The usual easy to spot symptom of a head problem is water boiling into your overflow. The overflow is intended to catch expansion but it should be a relatively smooth and temporary flow. If it's not and is "boiling" it's way in, you have issues. Likewise if you have your cap off and see bubbles after its warmed up. Both are caused by exhaust gas entering the coolant and over pressuring the system.

Obstructions can be anywhere in the system, including a failing water pump. A chemical flush that removes or at least makes a noticeable difference tells you if it's a build up problem and you may want to get the rad cleaned or replaced. if I'm not seeing evidence of a head issue I would likely start with the flush kit and chemical flush. Following that, test the coolant for gas in case the head is a problem but your not seeing it.

While it's not impossible that you're running lean it's unlikely. The computer will usually throw a code well before you get that lean.

Something to note, you mentioned that according to your app you are boiling at 212 degrees, the boiling point of water. However properly mixed with antifreeze 50/50, your coolant has a boiling point of around 225, with no pressure. With a presurized system, you don't actually boil until 240/250ish. If you are actually boiling at 212, you have nothing but water in your system. If Otoh it just sounds and looks like boiling what you're seeing is exhaust being forced into your coolant, and your back to a head issue.



And as a side note, if memory serves water cools just fine during a phase change, in fact it cools as fast as heat is added to it. Take any 5 liquids with a known but distinctly different boiling points and mix them up, then add heat. The mixture will heat up until the first boiling point is reached and then plateau as the mix boils. The addition of heat remains the same but the act of boiling will then remove heat at the same rate as its being added. Once all of that substance has boiled off you'll see the temperature rising again, until the next boiling point is reached, then temp will plateau again.

The reason boiling water won't adequately cool an engine is because the bubbles prevent the coolant from touching the metal as it should and keeps the heat from transferring to the liquid.

 

My head hurts now... but he is absolutely correct.Good write up.

 

Hey guys. Sorry for the lack of responses for a bit. I've been quite busy with work and other things. I intend on testing my coolant for exhaust gasses but haven't gotten to it just yet. I'll get back into it this coming weekend. Possibly sooner. Cheers.

 

Thanks for your detailed response.

Update:

Today I tested my coolant system for the presence of combustion gasses. The test with the blue liquid where you drain your radiator down a couple inches from the top, warm up the engine to operating temps and use the squeeze ball to pull air from the radiator through the blue liquid in the tube. That test. You are suppose to chooch on the radiator for two minutes and if the blue magically turns into Miller highlife, then you have combustion gasses in the system. I drained it down a bit and brought her up to 190*. I put the blue stuff in the tube and jammed it in the top of the radiator. I held the throttle open at about 2,000 RPM for a good while . If there was some exhaust gasses escaping into the system, I wanted them to build up. Worst case scenario type shit. I dropped her back down to idle and hit the squeeze ball for about 4 minutes, sucking air from the radiator through that blue stuff. It stayed as blue as when I put it in there. When I was satisfied, with my result, just for shits and grins, I took the little apparatus back by my exhaust and hooted on it a couple times. The shit turned yellow. So at least I know they didn't sell me Windex. Seems as if my head gasket is doing just fine. I'll be pulling my radiator. I suspect there is more shit packed inside it than what I can see. I blew a little compressed air through it and a good bit of grass seed came out. Like the fluffy stuff from taller wild grass. And I had been driving around in a field not too long ago. This stuff was NOT visible looking down between the A/C condenser and the radiator. It was inside the radiator between the little fins. The compressed air was bending some of the little aluminum fins though so I didn't want to go crazy with it. I will pull the radiator out and inspect it this weekend. If it's not the radiator, I think I'll just park my truck over on the north side of Milwaukee with the keys in it. Lol it probably wouldn't even get stolen. Stick shift...