Cold and fluxuating coolant operating temp

[migee]

Hi Guys,

One last thing on my truck I've been trying to work out. Hopefully nothing serious. In short the truck is a 99 3.0 V6. I just finished a rebuild after the Cam Sync seized.

I noticed that the coolant never got to the 1/2 mark where it normally would get to. Since the rebuild it only gets a 1/4 of the way up, and will fluctuate between that and the start of the cold bar. Here is the timeline on what happened related to the cooling system:

• New water pump, upper and lower hoses, thermostat (192) as part of my rebuild. All new fluids. Did a coolant flush before taking it out onto the road. Noticed issue when I first took it out for a real spin. Heater blows hot. Nothing wrong other than gauge being off at this point (runs fine).
• Checked my receipts. Noticed that I bought a alternate temp thermo? Checked my rockauto receipt: (BECK/ARNLEY Part # 1430674
  Alternate Temperature; OE Temperature Is 197; Temperature 192). I find this odd as the OE temp IS 192? Isn't it?
• Picked up new thermostat from a local store, parts desk told me 192 is OE and gave me a new thermo. Installed that, new gasket (again), and made sure that it was installed springs towards engine side). Opened rad cap to try to burp it.
• Same issue, thought gauge sensor was going. Hooked up a scanner to read the other coolant sensor - the ECM sensor. ECM shows that its not up to temp (goes to 185, then drops to 179 and repeats, every 15 seconds or so mainly when cruising I think).
• Stumped... I wonder if there is some air trapped in upper rad hose as I can shake it, and hear a bit of sloshing, not much, but some. After extensive searching I hear on these forums that 3.0's don't have issues with getting air trapped? I find this a bit odd as the upper hose IS a good amount higher than rad? When I take the rad cap off and start cold, no air comes out and coolant starts to run out after 15-20 seconds or so.

So basically that's where I am at. I may try to park on a steep hill to get more air out but I figured I've been driving like this for weeks now and it hasn't changed.

I thought headgaskets could be an issue but they weren't before, prior to the rebuild. Often HG's sound like they would raise the temp as well. Overflow is working fine and nothing crazy there.

 

[adsm08]

Sounds like low coolant to me.

I would make sure it is filled completely. The easiest way to do it at home with no special tools is to pop one of the heater hoses off at the heater core and pour coolant down the hose until it comes out the other end.

The surest way to do it is to get a vacuum bleeder/filler of some sort like the AirLift or Snap-On's Radkit/Radkit+, but those guys require a good air compressor and are kind of expensive.

 

[migee]

I'll give that a go if I have time tomorrow, thanks. The reservoir was going up after the engine was heated up (to as much as it can go at the moment) so I didn't think that would be the case.

Hopefully it is just that. I was also recommended by a friend to get an OEM stat which I might as well give a shot.

 

[adsm08]

Yeah, OEM t-stats are the best. I put a NAPA on in my 4.0 when I rebuilt it and I don't think it work right. Never really seems to get warm. When I get some motivation I'm going to change it out.

 

[JP02XLT]

My experience with Thermostats is sometimes you get one that opens and closes as it should at the right temps and other times you get the symptoms you describe. I have used Napa, Stant, Wagner and several others, it seems to be a quality issue that can be present with all brands. I put one of the flush coolant tee's in the heater core line to fill with like Adsm08 suggested, its quick & easy to fill it up and you dont have to worry about taking the line off of the heater core and possibly cracking the core. For the temporary, you could block part of the radiator off with cardboard to raise the temp, just adjust the amount blocked off accordingly, I would start with blocking 30% and see where that takes you.

JP02XLT

 

[RonD]

Stumped... I wonder if there is some air trapped in upper rad hose as I can shake it, and hear a bit of sloshing, not much, but some. After extensive searching I hear on these forums that 3.0's don't have issues with getting air trapped? I find this a bit odd as the upper hose IS a good amount higher than rad? When I take the rad cap off and start cold, no air comes out and coolant starts to run out after 15-20 seconds or so.

With rad cap off on cold engine no coolant should come out of the cap opening after starting.
You might get a "burp" of coolant coming out just after starting, no 15-20 second delay, but not a continuing flow.

Cold cooling system has no pressure, water "pump" just circulates coolant, it doesn't increase pressure.
And with t-stat closed there should be no circulation in the radiator anyway.
And with no t-stat coolant wouldn't come out the rad cap opening either unless lower rad was clogged.

Also the overflow level shouldn't change much, rad cap on, until coolant temp gets above 200degF.
As coolant warms(above 180degF) up it expands but rad cap holds it in the rad until cap pressure is reached, usually 14-16psi, at that time some coolant will flow into the overflow until pressure in rad is below rad cap rating.
Have you changed the rad cap recently?
Good thing to do when t-stat is changed.

I would do a "glove test" just to rule out extra pressure coming into the system, yes from a head gasket breach.
A small cylinder to cooling passage leak doesn't cause overheating until "air" displaces enough coolant and if the "air" is being burped out to overflow then it may not overheat at all, for now .
Glove test is pretty simple
Cold engine
rad cap off
Unplug coil, you want a no start
place latex glove or balloon over rad cap opening, needs to be a tight seal
remove overflow hose and block that opening, with you finger is fine if you have someone else to crank the engine over.

Crank engine, watch glove, if it bounces or starts to blow up you have a leak from a cylinder to the cooling system, could be head gasket or cracked head

This is a video of a "glove" test, however he didn't use a "glove", lol
http://www.youtube.com/watch?v=vFGquUimXro&feature=youtu.be

Yes, this confirmed a blown head gasket

Does the heater work in the cab?
Does it heat up as it should or does it seem weaker.
The heater hoses are the water pump by-pass, if the by-pass valve has a problem then coolant temp will go up and down.
Check both heater hoses to make sure they are the same temp, if one is much cooler than the other then by-pass or core is blocked.

 

[migee]

I would make sure it is filled completely. The easiest way to do it at home with no special tools is to pop one of the heater hoses off at the heater core and pour coolant down the hose until it comes out the other end.

I gave this a shot, I didn't pop off at the firewall but the one at the throttle that T's right off of the heater hose (its higher up and I knew that particular one was not stuck on). Any water I added came right out the other side.

My experience with Thermostats is sometimes you get one that opens and closes as it should at the right temps and other times you get the symptoms you describe.

Hopefully this is the case, though with the second new (although cheap brand) showing the same thing I'm not 100% convinced. I may try the cardboard later on to see if it helps put it to 192.

Headgasket stuff

You have me worried. However I looked at it today and not sure what to think. I put a solid rubber cap over the overflow outlet and a very tight fitting balloon over the neck. I cranked for over 5 seconds and it didn't budge at all. I verified it was holding air by putting a rubber line to the overflow outlet and blowing air in.

However, taking it all off and putting it back together, but with rad cap off. I just double checked and it slowly rises with the truck running and in about 10 seconds gets to the top. The rad cap looks to be in good condition. I suppose I can spring for another one as they are cheap anyway. Its made for 16lbs I think.

Does the heater work in the cab?

Yep. Honestly wtihout the gauge being off I wouldn't have noticed any difference or something off.

Check both heater hoses to make sure they are the same temp
I'll check next time I have her up to temp. Thanks.


Thanks for the help so far everyone really appreciate it. I think my next step is to replace the rad cap and thermo with OEM parts.

 

[RonD]

You need to crank it longer than 5 seconds.

You can even leave the coil connected and start the engine if you want, if balloon inflates you got a leak, although spark off is better, if you crank engine longer.
You said it takes 20 seconds for coolant to rise so I would crank engine at least that long if not a little longer.

The cooling system doesn't have any "extra" coolant anywhere, so the coolant rising with rad cap off has me puzzled.
I can see the water pump displacing some coolant from block/head to rad but that is actually against the flow, top rad hose is blocked by t-stat, lower rad hose is where water pump pulls out coolant, so against the flow.
A jiggle valve will allow a small amount of coolant into the upper rad hose, but wouldn't be that much, and water pump would suck it out the bottom hose in any case.

yup, a puzzler

 

[migee]

You need to crank it longer than 5 seconds.

You can even leave the coil connected and start the engine if you want, if balloon inflates you got a leak, although spark off is better, if you crank engine longer.
You said it takes 20 seconds for coolant to rise so I would crank engine at least that long if not a little longer.

The cooling system doesn't have any "extra" coolant anywhere, so the coolant rising with rad cap off has me puzzled.
I can see the water pump displacing some coolant from block/head to rad but that is actually against the flow, top rad hose is blocked by t-stat, lower rad hose is where water pump pulls out coolant, so against the flow.
A jiggle valve will allow a small amount of coolant into the upper rad hose, but wouldn't be that much, and water pump would suck it out the bottom hose in any case.

yup, a puzzler

I'll give it another go. Though I do feel that the balloon will inflate if running, after all the coolant dripping out is proving there is some pressure. I was wondering the same about the jiggle valve however yea.. doesnt make much sense. Perhaps the beginning of a HG giving out?

 

[RonD]

Cold cooling system has no pressure, so inflating glove or balloon means it is getting pressure from somewhere.
Only thing in the engine near a cooling passage that can develop pressure is the compression stroke of a cylinder.

You can idle an engine for quit a few minutes with rad cap off and shouldn't see any coolant coming out, normal pressure in a cooling system comes from coolant get hot, not warm but hot.

 

[migee]

Cold cooling system has no pressure, so inflating glove or balloon means it is getting pressure from somewhere.
Only thing in the engine near a cooling passage that can develop pressure is the compression stroke of a cylinder.

You can idle an engine for quit a few minutes with rad cap off and shouldn't see any coolant coming out, normal pressure in a cooling system comes from coolant get hot, not warm but hot.

Didn't get around to trying out another balloon. Though I double checked the truck after driving around today. Blew hot air fine. Checked hoses and both felt the same temp (just about hot enough to not be able to hold on to). I was wrong about the reservoir, it does not appear to change height. Lastly the upper hose was hot (and when jiggled still heard some sloshing).

Rond, what would you do at this point? Still go ahead with another new (but oem) thermo, and a new cap? Or would you just leave it and let it be?

 

[migee]

Only thing in the engine near a cooling passage that can develop pressure is the compression stroke of a cylinder.

One thing I'm curious about. I think in a manual I read for a ranger for some sort of troubleshooting to leave the 'Rad cap cocked open' and in another manual to force the rad cap to stay open with wire if the coolant rises when trying to burp out air. Should I give that a a go? I wonder why that would ever be recommended

Edit: appreciate the help so far, whether or not it can be solved!

 

[Rearanger]

However, taking it all off and putting it back together, but with rad cap off. I just double checked and it slowly rises with the truck running and in about 10 seconds gets to the top.

It's hard to check for head gasket/cracked head with thermostat installed as you will not see anything at the rad cap until thermostat opens, then it's too violent to assess. If your changing the thermostat anyway then go to Stant Superstat, they're better made and designed to keep temperature more stable.

To check for head problems I'd recommend removing the thermostat and re-installing the housing. When you start the engine you'll see bubbles right away at the rad opening if there is a problem. Filling coolant with heater hose disconnected (as mentioned) is a good way to get air out as the heater hose is behind the thermostat.

 

[migee]

Thanks Rearanger,

I'll try that out if I get a chance, haven't had time lately to follow up

 

[migee]

Just getting back to this thread to close it.

I ended up putting a genuine thermostat in along with new rad cap and the problem was solved right away. Havn't had issues since.