z31freakify

Hi guys here again with yet another ˟˟˟˟ing problem.
RIG: 1991 4Runner 3vze 2wd auto
Things done already: OEM Toyota Thermostat, burped, new hoses, new ECT, new water pump, new radiator,and new fan clutch, mostly oem parts exept for the hoses and rad.
I want to get this fixed and have no more problems
the thing is that when driving my temp starts going down from the half point and makes my OD to disingage and gets me pisst off it goes all the way down to half quarter almost to cold but the funny thing is that my heater still throws out hot air, not as hot as when my temp is on the half way tho. My rear heater started to throw nothing but cold air only in some occasions it throws out hot air mostly when my temp is on half ways. Another thing i notice is that after driving and stop the truck to see if my engine is hot but no the 3vze is warm to the tuch, its crazy but you can touch the lower radiator hose and its ice cold and top hose is hot and hard (you know what i mean) and the rad is hot from half up and ice cold from bottom down
what the hell can it be please help guys, i had a piece of card board covering half my radiator but took it off couse it got warm over here in El PAso TX. and did not want to risk overhating my yota but it help tremendesly kept my temp at a steady half way mark so anyone with the same problem and managed to fix it help please!

keithdphan

if top hose is hot and the bottom is cold as you describe. it means there is a serious clogg in the coolant lines. in most of the cases, it is the the thermostat being stuck/not opening. OEM toyota themostat allows a pinhole bypass before thermostat completely opening. most third party thermostat i've seen at parts store dont have this and would require you to drill a small hole. (I believe this allow the truck to get into operation temp faster.)

if this was my truck I would check the thermostat to see if it even works, install upside down, or other. its easy to get too, so I would do this first.

Remember when youre putting everything back together , burp the coolant lines with the heater temp switch set to the max heat to burp the heater core as you burp the mains.

z31freakify

I did that and the t-stat is working and also has that little hole with the pin in it i also was suggested by another yota driver to drill another hole at the six a-clock position meaning the opposite side from the oem hole but nothing Im thinking that it might be lower intake manifold cooling passeges are clogged up or something I flushed it my self by putting compressed air into every cooling line in the veichle the only one that was clogged up was the rear heater lines they were pretty clogged but uncloged them until the water with the compressed air came out clean and free of ristriction at this point i dont think it's even the t-stat what else can it be?

ksti

If the thermostat is working properly IMHO I would not drill another hole on the thermostat.
I just don't see it solving your issue.

I know you said it was a new radiator, but it still seems like a flow issue.

z31freakify

could it be my water pump? It's new no more than 7,000 miles on it, but would it not overheat my truck instead of cooling it down? I just don't know what the hell is going on this is a new thing for me never had this problem with other veichles not even the other mechanics dont know, thats why the yota driver told me to drill the other hole but no good

z31freakify

Here again still having the same problem I canceled the rear heater as i saw one of the hoses seapin antifreze thought i will solve the problem but no. Checked compression on all six cylinders they are all at 190 psi (with all sparkplugs removed) i was thinking it was a HG problem because my hoses swell up, i keep burping the coolant system but after driving it and burping it again more air comes out. My truck does not overheat, or has coolant in the oil, nor is it puking it trough the degas, what the hell can it be, oh almost forgot to mention i did a coolant pressure test and it passed and there is no exhaust gas in the coolant I did my HG like 15k ago my truck has 189,xxx

ksti

Hose's swelling up, sounds like a restriction somewhere. Before you did head gaskets, did you put any stop leak in the system at anytime?

z31freakify

no, bough it with the blown head gaskets and to my eye I did not see any stop leak anywhere in the block or the heads but then again my heads got rebuild acid dipped so there is no restriction in the heads and the weird part is that it does not overheat wich would be if something would be pluged up

z31freakify

any more thoughts on what it could be. I dont have the fan shroud can it somehow affect it in any way I dont have one either and can't find one on the u-pull it or on other junk yards and we have a ˟˟˟˟ load of junk yards in el paso over 50. like i said before if i cover half of the radiator with a piece of card board it helps alot keeps the temp on the half way mark and trans changes perfectly and it does not overheat and the engine feels hot like it should as on opposite without the card board the engine feels cool to the touch. i know for a fact it's not restriction if that were the case my engine would overheated, at this point i dont know

ksti

Then why to you think the hose's are swelling?. That just sounds like pressure building.
Have you put a thermometer in the radiator?

z31freakify

no i havent im going to do that today, and like i said even the engine feels cold the radiator feels warm not hot on top, cold on the bottom
it looks like my engine is running way to cold

GorgeRunner

Sounds like a thermostat issue to me. Make sure it's the right temperature and that it actually works(drop it in a pan of water heated to the temperature rating, like 180° and see if it opens). With the radiator cap off and engine running, can you see water moving through the radiator(water pump check). How about coolant/water ratio? If I put more than 50% coolant in my Toyota, it never gets to operating temperature.
The 3.0VZE on my 95 4Runner always seemed to run hot(new water pump, radiator, hoses) even though the heater output never seemed that hot.

z31freakify

you may be right with the 50/50 mix because i did put a whole gallon of 100% antifreze and the rest in water i will check that tomorow will try it with water to see how it goes oh and the t-stat does work, thanks man I totally forgot about 50/50 mix never cross my mind

ksti

To much antifreeze depending on motor can run hotter as this causes poor heat transfer.
Antifreeze main use is just that, to keep the cooling system from freezing.

z31freakify

water heats up way quicker than antifreze and i see that it might be the problem but the swollen water hoses I don't get it and after burping the cooling system I keep getting air bubbles what do yall think man is this crazy or what and officially I went bald from pulling my hair

rworegon

How many quarts does your radiator and cooling system hold? I'm guessing it's something like 10-11 quarts. So I doubt you have too much coolant in the system if you only added 4 quarts of coolant.

z31freakify

dont know exactly but it looks real thick dark green almost as if it was all antifreze

GorgeRunner

Drain the cooling system into a bucket and fill it with regular water and see what happens. You can put the stuff you drained back in later.

z31freakify

will do but it will have to be done tomorrow crosed fingers and hope it works

Gamefreakgc

x2 on draining the antifreeze. The color should be a neon green color when poured out. Any objects or brown rust is a red flag. It should be thicker than water but not too thick.

If I recall correctly (thermal resistance from high school...), too much coolant could do several things. If the thermal resistance is higher than water, it will not transfer heat very well and cause the engine to overheat (like a insulator). If the thermal resistance is lower than water, it will transfer too much heat and cause the engine to run cold. Having additives or rust in the coolant could disrupt this balance.

I think it's probably a t-stat issue though. If it opens too much the engine block will not keep coolant long enough to stay warm.