Burps, cold air, high speed heat, and a wacky temp gauge

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M

MinkWA

10 Year
Joined
Feb 4, 2014
Threads
2
Messages
34
Executive Summary

  • Assistance needed for troubleshooting No Heat problem
  • 1993 FJ80 purchased Monday - 258K miles
  • Cold air coming from heater vents during normal operation
  • When driving on freeway at higher speeds, hot air does finally come through
  • Hot air does come through when parked on incline during burping process.
  • After burping on incline, cold air returned when driving on flat ground.
  • Temp gauge has gone up to ~3/4 and then dropped back down immediately while driving on Wednesday.
  • Both the front and rear heat blows cold air.
  • Not sure if coolant is flowing well. When looking under the rad cap, it looks to be circulating a little, but not much.
  • Odd rattling sound coming from front end of truck while idling. Can only hear it while standing at the front of truck with hood open. Cannot pinpoint. Might be coming from water pump?

Troubleshooting done so far
  • Unsuccessfully tried to burp air out of cooling system on Monday, Tuesday
  • Parked on incline Wednesday to burp with rad cap off. Heater started blowing warm air almost immediately. Let truck run for ~20 minutes.
  • Pulled overflow cap after driving tonight and noticed air bubbles coming through the tank.
  • Swearing and name calling have had no impact on the performance of the vehicle.

What are my next steps here? My research on this site has led me to multiple potential issues, none of which describe exactly my issue.

  • System still needs to be burped. I might just suck at this part.
  • Thermostat needs to be replaced.
  • HG - please don't be this.
  • Water pump is failing.

If any of you can put me on the correct next step for troubleshooting this, please let me know. I am a little frustrated today.



Long version -

Well, I'm new here. I just bought a 93 Cruiser on Monday. It's a beautiful green monster.

During the test drive and look over, there was a definite lack of heat. The previous owner explained how he recently flushed the radiator, and we attempted to burp it. But, it was 19 degrees out and windy, and 9:30 at night.

I went ahead and bought it, hoping it just needed the burp to get the heat running. This may or may not have been a good idea. Still TBD.

On the way home, which was about a 70 mile drive on the freeway, the heat kicked on and started working. My excitement was cut short when I pulled off the freeway to fill it with gas, and once I slowed down the heater vents started blowing cold air again. After getting back on the freeway, the heater kicked on. The temp needle remained in the center of the gauge the entire trip, or at least every time I looked down at it.

On Tuesday, I parked on an incline, and immediately tried to burp it incorrectly. I left the rad cap on. No progress made, but plenty of time wasted.

Tonight, after reading and confirming proper burping etiquette, I drove the front end up on some ramps, let the vehicle warm up, and opened the rad cap. At this point, on the incline, the heater starting blowing hot air immediately. The temp gauge stayed in the center. I let the truck run for ~20 minutes in this position.

I backed down off the ramps and took the cruiser for a spin. Within a few minutes on flat ground, the cold air was blowing again. I pulled on to the freeway, and after a few minutes, the heater was blowing hot air again.

Another few minutes of freeway driving, and I noticed the temp needle spiked up to about 3/4 of the way up the gauge, and then slowly came down. The heater was going in and out at this point, but mainly no heat. The temp gauge moved up and down a few more times as I pulled off the freeway and creeped home on the side streets. Once I got home, I pulled the cap on the overflow tank and I could definitely see a stream of bubbles coming through on a regular basis.

At this point, I am not sure what to check next. I have read a ton of posts here, but none seem to have any info related to the heat coming through at freeway speeds or confirmation that the heater works when running on the incline but not on flat ground.
 
I'll bet there's still air in from the PO's flushing job. Stay on the incline and let her cook with the radiator cap loosened., you will need to top off the radiator until full and make sure the overflow has its fill, too. All with proper antifreeze mic of course.

Remember you have a rear heater, too, so it should also be running along with the main heater. Those lines back to it are long and the big reason why you need the incline. Get a steeper incline maybe, also.

Unlikely its the water pump. Look for a worn idler pulley maybe, loose belt, etc.

If it was the HG, she would've gone past 3/4, which is why I'm leaning towards air in the system. How's the underside of the oil fill cap look. If it's like oil, you're OK. Milkshake look is bad.

Hang in there.
 
The belt on the water pump doesn't appear to be loose. The oil under the fill cap looks good.

I think it still has air in it. I will need to find a better incline to use. Any other tips for clearing the air? Should I rev the motor a bit while on the incline? I feel like I have cleared a bunch of air in my attempts so far. I must have gone through a gallon of coolant already trying to fill it, although some of that has ended up on the ground.
 
Nothing special needed other than a steep enough incline and patience, if you've got the rad cap loosened. It's a matter of letting the air out while filling that space filled with air now with coolant. Be sure you have the heat temp slider on the HVAC controls all the way hot to ensure max flow through the lines into the cabin.

If you've added close to a gallon of coolant, then there was a lot of air in the system to start with, which explains your symptoms.

Also, be aware that the stock water temp gauge is factory "deadened" so that it's slow to react. It's pretty close to an idiot light the way Mr. T made it -- search for the Raventai water temp mod here for more info. If it was in bad shape, it would've gone into the red at the top of the scale, so only 3/4 up was actually a good sign.
 
Updates for the weekend.

First off, cheers to everyone here. This forum is a great resource. :flipoff2:

Burped the hell out of the green monster this weekend. Found a decent incline in an empty parking lot down the road from my house and ran it with the rad cap loosened. Lots of spillover from me being lazy when filling the radiator.

On Sunday, I took a funnel and duct taped the bottom to make it thick enough to create a seal in the radiator opening. I filled it partially with coolant, started the truck, and got some more air out. Squeezing the outlet house at the top drivers side of the radiator helped move more air along.

I drove my wife to work in the snow this morning, let it cool down, and filled the radiator up. I did the same thing later in the afternoon. It snowed here in Snohomish County Saturday night, so I was able to play around in the snow after dropping the wife off.

Heat was intermittent pretty much all weekend, similar to before. I think I am closer now, because tonight I was getting heat at idle. The engine temp gauge/idiot light stays pretty much even the entire time. I have seen it rise a couple of times to ~3/4, and then drop right back down.

What's the difference between 3/4 and red line on this gauge? I definitely am going to look into the digital temp gauge or the cluster gauge mod.

I have had a lot of spillover out of overflow tank. My engine bay smells wonderful as a result. I am going to have to find a good way to clean the splatter out.

I am extremely paranoid about the HG issue after reading post after post about it. I went to autozone and rented a block tester. I don't think I can attach pics yet, so I am just going to link to this album - Block Test Results

I also did the "bubble" test based on this post - https://forum.ih8mud.com/showpost.php?p=1335407&postcount=11

I saw no bubbles in the overflow when revved up. There are bubbles at idle, but none at higher revs.
 
Took the cruiser to return the block tester tonight. Heat was there for a bit, then went away after a mile or so. After getting to autozone to find out they had closed, I headed back home. The heat returned for the drive back. When I got home, the truck was idling rough in the driveway.

Things are not looking good right now. No coolant smell in the exhaust yet, but the writing is on the wall with some of these symptoms. I am going to send out for a blackstone oil analysis.

I think there is a good cruiser shop just a few miles from my house - Torfab. I might give them a call tomorrow.
 
Gotta get to work, will read more throughly and think to add anything else later....

Makes me suspect something weird if the air isn't out of the system yet. Like a rusted out rear heater line, a leaky radiator, PHH maybe or some other way -- other than a head gasket is what I'm saying. The oil test will tell the tale, but in the absence of other symptoms still doesn't seem indicated to me.
 
I am going to seeing by Toyota and pick up an OEM thermostat and rad cap today. Not sure if I will get the chance to put the tstat in today with snow on the ground.
 
TLDR; I had a similar problem with another car. Turns out to be a crack in plastic part of radiator. I'd check for steam puffing up randomly once your truck is nearing operating temperature. On mine it would spray/vent out the front of the grill and made a mess in the clean-ish engine bay.

Long story:
Completely different car but similar problem with cold air when idling in my '98 Lexus GS400 (sedan). Turned out to be a hairline crack maybe 3-4" wide that developed/worsened over the course of a month or so and was spewing/spraying coolant out onto the front/hood inside whenever the car got warm. The crack was at the plastic part of the radiator just near the cap on top. I too had no heat suddenly when the coolant had reached low enough volume in the engine one day and same symptoms of driving/heat/idle/cold air. New radiator and leveling off the coolant in the overflow tank, so far seems to be fine now.

While your problem seems to be related but on a more possibly complex level I'd also just repeat on checking for any tiny leaks or cracks around any obvious areas first. It is quite possible that the truck is steaming off/spraying out the coolant whenever it is reaching high heat and causing you to endless burp/top it off (as a result of always losing coolant every drive).
 
Last edited:
Stardate 02102014.

Drove it in to work today. Temp gauge didn't move at all that I saw. I am tired of watching that thing like a hawk.

Looking back on everything, the only common, confirmed issue I have is I am losing coolant. Today, there was some definite coolant splatter under the hood. I checked in there after I got to work, but I cannot tell if it is coming from the overflow or somewhere else.

What are the symptoms of a bad rad cap? Could I be leaking coolant from there?

What would cause coolant to come out of the overflow tank? Would overflow tank spillover only occur then the overflow tank is filled to the brim? My overflow tank appeared to only be slightly higher than the FULL line this morning.
 
If you fill the overflow to the brim, it will spill whenever it gets hot. The line for Hot fill is further down and the Cool fill line even further down. So if you've been filling to the brim, that's why it keeps overflowing. You have to leave room for expansion.

As for the gauge, in stock form it's pretty useless and will go into the red as about the only indication you're likely to get, which is almost too late. The fact that it doesn't go more than 3/4 is actually one of the signs it's probably not the HG. In 95+ OBDII trucks, you can hook up a Scangauge easily to read true temps, but it's more complex in a 93, as you'd have to install a sensor, etc IIRC along with a separate gauge.
 
Thanks greentruck. Let me clarify on the overflow tank -

I have not filled it to the brim, I leave it somewhere between the low and full marks.

My question is, when would the overflow tank spillover? Would the entire tank have to fill up, and then coolant would then start seeping out of the spillover line?

I am looking for the digital temp gauge thread I found the other day. I am going to move on ordering that solution right now so I can get more accuracy on the water temp readings.
 
Google "Mityvac MV4560 Radiator/Cooling System and Pressure Test Kit" on amazon (link was to long). This is what I used to test my radiator cap and pressure test the system for leaks. Downside is the system has to be full to test. The pump does not put out any volume. There are high volume pumps you can get to test before you put the fluid back in.

Alternatively buy a new cap for $12 CND. Prob half the price State side.
 
I am taking my lunch break to head to Toyota of Kirkland and grab a tstat and rad cap right now.
 
I had similar loss of coolant for a few months that I watched like a hawk until finally it got bad enough to leave a trace. It was the top crimp seam on the radiator itself, the o-ring had finally given out. This was after replacing all the less expensive items like the all the coolant hoses and t-stat. I went ahead and replaced the water pump while I did the radiator. Hope that is all yours is. Good luck in your search!
 
New rad cap is on. Too late to get through the t-stat install tonight. I need to clean out the engine bay so I can pinpoint any coolant leaks. Might work on that tomorrow.

Tonight, after driving home from work (~15 miles, mostly freeway), I noticed the idle was a little rough, and it idled around 1000 rpm instead of the normal 800 rpm when warm. I noticed the same thing last night as well. Since the truck is new to me, I don't have a historical baseline to compare it to.
 
Another note - talking to a buddy of mine, he suggested taping a soda bottle to the spill over tube coming out of the overflow tank. That would help isolate the spillover from any other leaks, so I can rule out the spillover as causing the splatter.

Any other tips for finding coolant leaks?
 
It's mostly a matter of patiently tracking down the leak now. Cleaning things up is a good start, as that will help. I'd start with that, get it full of coolant as best possible, then start and let it idle. If you're lucky, you'll see a drip underneath. I would also inspect the radiator as thoroughly as possible. Then it's on the the various hoses.

After it's all clean, it's probably also worth sliding underneath to see what you can of the rear heater lines. These tend to rust in high-salt areas and are hard to get to or even see in some places.
 
Update for the day.

Drove to work and back. On the way back, my temp gauge rose up past 3/4 and barely touched the red line while sitting in heavy traffic on the freeway. It dropped back down after ~30 seconds, but I am extremely worried. The engine doesn't seem to be running as smooth as last week. I won't be driving it the rest of the week.

Heading out to get some foaming engine cleaner shortly. It's pouring rain here in good old western Washington.

Is there a way for me to check and see if the PO used some sort of stop leak? How would I check for that?

Also, how do I check for a clogged/gunky radiator? I will need to search the forum for that tonight.

I think I will pull the #6 plug tonight for a visual inspection. Not likely to get much under vehicle time with the cleaning and subsequent rinsing, as that will be dripping off for a bit.
 
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