Maverick

I'm having idle problems due to air pockets in my coolant system on my 92 4x4 (2.4L). The idle surges up and down at various times, and seems to stop, most of the time when the truck is warmed up, but not always. How do I get any air pokets out of the system? And has anyone else had such a problem. Thanks in advance.

M

Highland Runner

The only problem I had from air trapped (3.0) was overheating. I took the upper rad hose off and poured the coolant down in. This is the only way to get the air pockets out.

Maverick

Take the top hose off and pour coolant in the hose then reattach, and continue filling the rad.?

MTL_4runner

Have you replaced the therostat lately?
If no you might try installing a new one and drill (3) 1/8" holes at 120 degree angle from each other in the new one. That way there is plenty of ability for air to be removed from the system and prevent the pockets of steam when refilling or flushing it. The small holes will not affect warmup very much at all.

Maverick

I put a new one in this past summer, but a new one with some holes sounds like a good idea. Did you do it or know someone who did, and had good results?

M

MTL_4runner

I used to be a mechanic and have done that in the past on troublesome vehicles where it was difficult to purge the system of air. Works pretty well but you need to be very careful not to bend the edges when you drill the holes. One of the 3 will already be there (take out the little brass piece which sits in there with a pair of cutters or a dremel cutter tool), you just need to drill the other 2 at 120 degree angles away from it and about the same radius away from the center of the thermostat. Start with a smaller bit, say 1/16" and work up to 1/8" so the unit looks uniform.

Fahrenheit 451

If you haven't had a head off or drained a whole lot of the fluid out of the cooling system I'm not sure how you would get air locked. Let the system cool down and then slowly turn the radiator cap and see how much pressure releases. After doing so, take a good whiff of the radiator for exhaust odors. With the air in the system and the odd idling, I'm guessing you have a headgasket going/gone bad and are getting exhaust gases in the cooling system and possibly some crossover of exhaust gases between a couple cylinders. One thing the 22re's are known for is the eventuallity of the headgasket letting loose. The aluminum head on a cast block gets pretty tough on them since they move at different rates. I'm also guessing that the reason it gets better as the truck warms up is the result of the head's expansion taking up the slack in whatever is wrong with the gasket. If this is the problem, it won't last for long.
Not trying to rain bad news, but if it was an airlock problem, the truck should be overheating pretty quickly whereas a headgasket can be pretty sneaky sometimes. The exhuast gas going into the cooling system can cause overheating when it gets bad enough, but it might also be relieving much of the pressure out of the overflow. When you crack the cap, listen for pressure being blown into the overflow reservoir.

MTL_4runner

Perform a leakdown and you will know if it is a headgasket for sure.

CTB

Also, whenever I drain and refill my coolant, I leave the radiator cap off and let the truck idle for a while...it eventually purges almost all of the air out of the system. Continue filling your radiator as it idles, and keep a catch pan underneath the vehicle to catch and anti-freeze that bubbles over. Turn on the heater in the cab to get the antifreeze moving through the heater core.

PirateFins

I read about this on another board and tried it, except I left the holes at 1/16". It help get the air out, but it caused the truck to run way too cool. The temp needle wouldn't go past the "C" mark, and that was with a new 185* t-stat. I just replaced the t-stat with a 2 stage Toyota OEM t-stat. I also put in a Tee in the upper heater hose with a shut-off valve to bleed out the air. That worked well.

MTL_4runner

How many holes did you put in there?
I can't possibly imagine (3) 1/16" holes caused it to never warm up.
A full open thermostat flows alot of coolant through it.
I agree with leaving them at 1/16 and not going to 1/8 and using a 190* t-stat.
Do you have a pic of the 2-stage t-stat? .....I'd like to see that.

A heater hose purge is good too but it must be sturdy enough to hold up to 15+ psi in the cooling system.

Maverick

Ok, after much time spent on this hypothesis I have come to a conclusion. I think the problem is that after installing a 3in. body lift, the over flow tank sits alittle higher (like 1.5 inches) than the rad. Once the truck heats up, the coolant goes into the overflow tank, and once the truck cools the coolant stays in the overflow tank and doesn't return to the rad like it should. This leaves the rad. low on coolant. Thus, causing my idle problems. But the question is, how do I fix that problem? I've checked all the hoses and didn't see an obstruction or crack. Thanks in advance

M

CTB

I thought this stuff all worked on vacuum, so I didn't think it would matter if the overflow was a little higher than the radiator...but, I may very well be wrong.

Could you fab up some small brackets to lower the overflow and make its height even with the radiator?

Maverick

Well, that's what I thought at first too, but I don't think I can lower the overflow tank b/c it rests directly onto the wheel well. I don't know what to do, or maybe there is a small crack in one of the hoses or something, but the rad. is drawing air back into it from somewhere, instead of coolant, so I guess I have to replace the hoses first. What do you think?

M

TechWrench

The balance between the levels in the rad and the overflow tank should be automatic. If the system is sealed, and the rad cap is working properly, the 'vacuum' in the system will adjust according to coolant temp. As for the air in the system, most systems now have a bleed port somewere on the the engine to purge the excess air from the system. Look in the area of the thermostat housing or in the intake manifold area. If it has one, fill the rad while cold, and then open the bleed port. I usually then apply air pressure to the rad fill neck ( blow in it ), and this will force the excess air out the bleed port. You may have to do this several times, after running up to temp to circulate the coolant properly.

If you continue to have a level problem with the overflow tank, you should have the system pressure checked for leaks. This should be done both cold and hot.

Highland Runner

Sounds like its leaking air at the cap. Buy a new one, they are cheap. Also make sure there is no crud where the rubber seal touches the radiator.

Maverick

Ok, I'm just about ready to get out the hammer; seriously! I installed a new theromostat, checked the hoses, purged all the air out of the system, bought a new rad. cap and the problem persists. All of the coolant is being pushed out of the rad. and into the overflow tank, and not being vacumed back into the rad. So the coolant levels are not equalizing, thus leaving my rad. low. I haven't had it pressure checked yet, but if it had a leak wouldn't I be able to see coolant being sprayed or driping out of the leak once it gets hot? I just don't know what to do. I've also noticed a frequent change in the temp. of the air coming from the heater. I was driving the truck home tonight and the air coming out of the vents kept getting hot, warm, the slightly cool, then repeating the cycle. I don't know if that helps out or not. But something is up and I don't like it at all. Talk soon Thanks in advance for everything.

M

Fahrenheit 451

>>All of the coolant is being pushed out of the rad. and into the overflow tank<<

I know you don't want to hear it, but I can pretty much guarantee you that you have a bad headgasket and are getting exhaust in the cooling system. It is pressurizing the system and blowing the pressure out the overflow. Don't let it go so far that it lets loose completely out in the middle of nowhere. Heck, don't let it happen in the middle of somewhere. You can wind up warping the head and damaging the oil seal rings on the pistons from the overheating.

MTL_4runner

If you did all that I'm afraid I have to concur with Fahrenheit 451 on the headgasket problem. That is the only reason your system could be overpressurizing to such an extent that everything ends up in the overflow tank. When you replace the HG make sure to replace the headbolts with aftermarket studs to prevent the problem again.

Fahrenheit 451

>>When you replace the HG make sure to replace the headbolts with aftermarket studs to prevent the problem again<<

Make sure and get the right torque specs for the studs too. The torque for them is much higher than bolts (around 83ftlbs instead of 55 I think). Trust me on this one. I just went through it. I had the headgasket replaced and the guy only torqued the studs to bolt settings. The second mechanic actually called the company and got the right specs. Don't be like me and have to pay for two headgaskets because the first guy got it wrong