b18a1, sometimes overheats, temp shoots up and down, please help.

I have a 91 da9 with the b18a1. This happens all the time. I will be driving normally, and the temp gauge will fluctuate from normal to overheating. It acts strange, sometimes I can give it gas get the rpm’s up and it will go right back to normal. Sometimes I can turn the blower on and it will go back to normal. Sometimes neither one of these seem to work at first but it will go right back down to normal. Also the lower rad hose never even got warm. So I replaced the thermostat and gasket, the rad cap, and put coolant in it. Ran the rpms up and squeezed the lower hose to remove all the air from the system. Its still doing the same thing.it is blowing coolant into the overflow. Like I said, it doesn’t overheat all the time, I can be driving for a while before it happens.

After idling a while, if I turn the blower on the air will be cold and I have to get the rpms up to get heat out the vents.

New thermostat
New rad cap
No air in the system
No smoke out the exhaust
No creamy oil
Blowing coolant into the overflow

Help please before I lose my mind?

Did you use a honda thermostat? Sounds like either its sticking or there is still air in the system. With the engine off crack the bleeder on the head and make sure no air bubbles come out. Then remove the rad cap and run the engine until you get heat and see if that works. If not, put another thermostat in it.

i used a stant replacement from advance auto. new rad cap too. i can hold the rpms at 2000 and add coolant, it will bubble and bubble all day. never seems to stop

Go OEM. Aftermarket sucks. Especially those replacement parts.

oem may be better but there is absolutely no reason why a brand new stant thermostat wouldnt work.

now to remove air from the system, do i crack that bleeder untill a solid stream comes out? whats the deal with my lower hose staying cold and pressurised?

[QUOTE=90’teg_boy;2199341]oem may be better but there is absolutely no reason why a brand new stant thermostat wouldnt work.

now to remove air from the system, do i crack that bleeder untill a solid stream comes out? whats the deal with my lower hose staying cold and pressurised?[/QUOTE]

Don’t be so sure, I have seen many aftermarket thermostats crap out in no time at all. Put a Honda one in, bleed it, and I can just about guarantee your problem will be solved.

And not just aftermarket thermostats. I bought a brand new “Raybestos” brand inner tie rod. Right after the install, it started clicking when I turned. After replacing it with an OEM one, clicking went away. Other, my rear main seal and both cam seals were aftermarket and started leaking within a year. AND I can give you another paragraph of “other” aftermarket stuff I bought that crapped out, but I won’t.

NOTE: Yes… I’m sure not ALL aftermarkets are bad. example: my Starter still holding up since 2009. I try to go OEM as much as my pocket book lets me. They fit like a glove on our cars. Last longer too.

Hope you can change your mind about things. And about the bleeding, yes until its a steady flow with NO bubbles. Or you can just bleed it by letting the engine idle and remove the rad cap and air it out there. The lower hose staying cold could be your Tstat.

now it is overheating constantly and at startup for a lil bit it smokes. found an entire parts car with a good motor for 400, just gonna swap motors. mine is somehow losing oil rapidly, like a quart and a haldf in 2 days, but its not leaking or smoking bad.

Dude are your fans coming on??? I didnt see anyone say anything about fans??? Its your fans or fan switch, thermostat maybe u put it backwards or a really cheap one…or your rad is clogged

Everything mentioned could be the possible problem except for the fans or fan switch. My fans never come on at all (they don’t work… possible fan relay) and the engine never overheats.

its ur freakin fans bro…hahaa get that shit fixeddd see if there connected first if they are and they dont come on change that switchhh or it cud be the fan itself…get a voltmeter in those wires and see if u get voltage

Based on the original post I would say the symptoms are coolant related and nothing to do with the fans. Although non-working fans can cause overheating it is usually only noticed at idle and it does not have any change when you rev the engine. Still wouldn’t hurt to check them though. To the OP, you said now it smokes on start up? Is it smoking from the engine? Sounds like maybe you have a coolant/oil leak somwhere. You may indeed need a new engine if it has overheated enough but I would try to figure out why it is overheating before you just go ahead and swap the engine. You might end up right back where you started if it keeps overheating.

Did u miss when i said your rad is probably clogged…simple thingg i do when ive tried everything n still cant find the problem i go to mobil by my house and they inspect the problem for 30$ sometimes even free if its really easy to find and then i just fix it myself…

used to happen to me till i got a oem thermostat, dont go aftermarket it only lasted me a year. and make sure u bleed it and both hoses are hot. I bled it by leaving radiator cap open and waiting for fans to turn on, U are gonna have to raise rpm so u wont have to wait that long.

I have a simuilar problem like that. I took off both fans for sometime and somehow my temp started to overheat when I was in park like at a drive thru or something. When I take off it starts to cool down a bit. But everytime at a stop light/sign. It overheats again. So I put 1 of the fans back on which was the cooling fan. Not the ac 1. Now I get no problems with overheating at all.

[QUOTE=90’teg_boy;2199333] it will bubble and bubble all day. never seems to stop[/QUOTE] blown head gasket or cracked sleeve. 94

well, everyone here seems to be going off on tangents as to what the problem may be.you mentioned you aren’t getting heat. yet when you rev it, you get some. what i want you to do is, with the engine at operating temp, and the heater on max, have a feel on the inlet hose to your heater core. then, have a feel on the outlet hose. if the inlet feels hot while the outlet feels cool(er), you have a clogged heater core. this would cause your symptoms. and since you mentioned you aren’t getting heat, i bet it is the problem. if you aren’t getting heat and are overheating, it is a circulation problem. the placement of the heater core makes a likely candidate. if both the inlet hose and outlet hose feel cool at operating temp, you have blockage somewhere else. possibly the t-stat. a plugged heater core would also cause your constant bubbling through the bleeder screw, as it would be forcing the coolant back through it.
do that simple check and report back

and don’t freak out and replace the engine. first, let’s find the problem. then, let’s correct it.
and oh yea, although i highly doubt it’s what’s causing your issue and i know it’s winter and all, but get your fan working properly.