ej257 shortblock
MY 98 ej25 DOHC NA mechanical lash adjustment heads
ej20g intake manifold, and turbo, intercooler, wiring harness and radiator

no hood scoop in FL

was overheating but problem would subside when accelerating (when more air was on radiator)

i thought it was my thermosta, so on two diff occasions i pulled it out and heated it up and it would start to open at 190 deg F. then finally when trhe problem was still happening i cut out the thermostat spring and just used the plate so it was in sense open all the time. it hasn't happened again but thats just because it doesn;t get to temp.

the other thing is that it will push out coolant from the coolant overflow. the plastic one. not the hard one. before i put a 1.3 bar cap on. it would push out the .9 cap and be boiling in the plastic resevoir after a hard run.

so i figured that i had a blown head gasket. pretty crazy with less than 5k miles on it. but the heads i got were from a junkyard, but i checked the plane of the head and was in spec

so i got new STi head gaskets and then i did a leak down test tonight and all 4 were good, and even if that wasn't accurate there would be bubbles in the hard resevoir right? which there wasn't

so maybe i just need a larger radiator, no scoop can;t be helping

front mount should be here shortly, should drop intake temps some. lol

HELP

my fans don't keep up really...that's why I've tracked down JDM radiators but I think I've decided on koyo seeing the future plans of my car :devil:

thats what i was leaning to, are your fans working.

well like i said with the thermostat open it doesn;t get to temp, i think i will put a spare one in that tests out too,

but yeah both fans were working fine, but i will further inspect that avenue

any other ideas?

oh and i forgot to add that when it would be overheating, i would feel the 2 hoses to the radiator and the top would be hot while the bottom would be cold.
thats why i cut the thermostat

if the top is hot and the bottom is cold, then you radiator is cloged and water is not flowin enough. I believe its time for a new radiator.

i'll try flushing out the radiator, becasue i when i had both hoses off last time i kept pouring water into the top hoseand it would pour out the bottom hose out the thermostat housing

you are running on the RS radiator correct? it cant keep up with a turbo motor.

no the radiator and entire cooling system are from a 94 wrx ra

id say intercooler not getting air then, its just acting like a heat sink, heating up and holding it in.

Have you confirmed 100% your fans turn on when needed?

Wire your fans to a switch and run them 100% (all the time) and drive around town and see if you overheat. As a test.

^^^^what he said, before you buy the koyo.

thanks, i will try that

ok so i flushed out the radiator and i don;t think it was clogged

i also put the old thermostat back in

i drove around town and it was fine, right in the middle of the gauge

but when i shut down it will push coolant out the plastic overflow

this is with the 1.3 cap

But did you check the fans? What is the current temperature there right now?

And actually, pushing coolant out is "kinda" normal. Since you come to a complete stop and turn off the engine, the water suddenly cant get any cooler, and it expands so it blows out into your overflow tank. As it cools, then the engine should draw the coolant back into the cooling system.

Since you have a hacked up system, are your fans staying on when you shut off the car? ALOT of vehicles will keep the radiator fans on AFTER you shut off the motor just because of what I was talking about.

65F earlier this afternoon here
i have never heard the fans be on after i turn the car off

perhaps i can have a seperate timer fan controller
1 all the time on while car is running
2 maybe for like 10 minutes after the car shuts off

becaue i carry a 2 gal jug of water with me. when i come back from stopping at a store or something, there will be a large puddle under the front, that was pushed out from the plastic resevoir

maybe i add too much water each time and it keeps putting it out
but if i don;t add water, thats when it overheats

right now airflow on the radiator is unobstructed
there is no condenser in the way and the front mount isn;t here yet

will the benefit of much lower intake temps conflict with diminished airflow

could a turbo timer be used for the fans

Air is either trapped at the water pump (needs a good burp) or you have headgasket letting in a little combustion gas and it gets trapped in the water pump until you rev the motor.

Try unconnecting the top Rad. hose at the Rad. and filling it. then connect and top off the upper water tank ect.
It really sounds like air is slowly getting in (H.G.) the water and screwing up the Waterpump.
Take the thermostat out (remove the center and replace) for a temp. fix.
I've been through this and it's very frustrating :(

Sounds like a head gasket or worse.

An "easy" way to see if you have a head gasket leak, or cracked block or head (ie, exhaust gasses getting into your cooling system) is what I have done. Be VERY CAREFUL. I do not reccomend this if you have any reservations about it!

Drive around and get the motor hot and park somewhere near a working hose.

With the motor running, remove the radiator cap (I am assuming you have a radiator cap of somesort). Cover your self head to toe with protective gear. The water is going to come GUSHING out of the coolant system. It will burn the hell out of you if you stand over it! Remember it is boiling water.

OK, now you have a HOT engine, and the radiator cap off.

IF you have a gasket leak, or similar, your radiator will be pushing air bubbles out. It should be VERY noticable. As in, "what the hell is going on?" You can actually get burned if you put your hand over the radiator cap. I know.....

So, if this is what you are getting, uh... pull the motor.

i thought it was head gasket too at first, i even ordered new 257 headgaskets and i was about to pull the motor when i decided to do a leak down test first and all 4 had 0% loss, plus there is no white smoke, nor oil and coolant cross contamination

when doing the leakdown test i had the cap off of the metal resevoir and i believe that if i had a faulty head gasket that there should be bubbles visible

not to mention that when i fill my coolant back up after draining it, i fill the last 1/2 gallon with the car running and i don;t see any bubbles through the cap so from what i see i have no reason to suspect exhaust gasses are pressurizing the coolant, just my 1.3 cap and no hood scoop

before when i had the .9 it would leak out the cap. thats why i got thew 1.3

oh and after a blast tonight iwhen i came back to the parking lot, the fans were running when i popped the hood and the temp hasn;t been high

OK. I give you a personal "?" cause I am done with my opinions. I wish you the best but I am out of ideas!

And I do know the frustration you are suffering. I pulled a motor 4 times in 3 days because of a exhuast leak into the coolant. And never did find the problem. Just lots of $ down the drain.

Good luck!

Doug

i appreciate all your input reddevil

although i think the real issue here is the coolant being pushed out, or higher than normal coolant pressure, i think i have identified that it isn't being pressurized from exhaust gasses

so what is the solution then, do i just stick with a .9 cap that constantly leaks on hard runs or what?

can you cap off the expansion into the plastic resevoir entirely, (sounds like a bad idea)

any insight would be greatly appreciated

It sounds to me like the system is just taking on more heat than it can handle. I think your number one issue is the lack of a hood scoop. Not only does a hood scoop let air onto the intercooler, it also marginally helps dissipate the heat generated by the turbo. Until you get a front mount, you are going to continue to have this problem.

Furthermore, you are likely making the situation worse by overfilling the coolant, and thus the constant overflow. It runs hot when at the proper level because it just can't handle all the heat. When you add more coolant, it just makes it worse.

And I am sorry to say that you may have already ruined this engine. Last year around this time, I was driving home from Thanksgiving through a whiteout and my thermostat stuck. My car got hot for about 100 miles before I could get to a service station and thaw out the thermostat. I was NEVER in the red, not once, just 2/3 of the way up the gauge. Everything seemed fine until about a month later. Out of the blue, the car started eating a quart of oil a week. I had scorched my bearings and done the damage back in November. When I cracked the block in January, I had 3 spun crank bearings. How the car kept running is beyond me, but my engine was borked...

i was also thinking that hhaving a fdront mount and thereby decreasing the intake temps greatly, would take some of the stress off of the cooling system

but seeing how the front mount would decrease airflow to the radiator, should i get more powerful fans... allthough the trunk mount radiator in the kumakubo rear drive D1 impreza is pretty sweet

as for overfilling the coolant i noticed that if i don't refill what is pushed out, it doesn;t push any more out on subsequent runs, or hasn;t today and temp is normal

there is less than 5000 miles on the block and at any point that the needle went up, if it didn;t come back down right away i shut down to let cool, i have never actually had it boil over or anything so bad. i think the turbo uses some oil though

I really don't think it has anything to do with intercooler, radiator efficiency, fan function or anything but waterpump getting water and air mixed.
Does this tend to overheat when coasting after regular or hard driving?
If I understand correct, when he revs the engine it cools.
I might be wrong, but I've experienced this more than once.

it may be the water pump, but it makes no noise and it isn;t leaking

before i intalled it to the new shortblock, i inspected it and it checked out

ok so it still overheats some. i don;t understand it.
doesn;t seem to be any coorelation between it and wind on the radiator,
it won;t overheat at idle

it doesn;t always overheat when i boost
but more likely to overheat when i boost
but sometimes it will just randomly heat up

i still think it has to do with a lack of proper coolant flow in the system

i tried flushing out my radiator and that didn;t seem to help and water poured out as fast as i sprayed it in anyway

i know its not my thermostat

but when it overheats i feel the top hose and its hot and the bottom is cold

somebody have the majic answer please

When you put the heads on, how well did the coolant passages match up between the gaskets and the heads/block?

Have you had your coolant system checked for leaks? Any loss of pressure would certainly cause boiling.

not it

nobody has any more ideas. please

Headgasket

ok so it still overheats some. i don;t understand it.
doesn;t seem to be any coorelation between it and wind on the radiator,
it won;t overheat at idle

it doesn;t always overheat when i boost
but more likely to overheat when i boost
but sometimes it will just randomly heat up

i still think it has to do with a lack of proper coolant flow in the system

i tried flushing out my radiator and that didn;t seem to help and water poured out as fast as i sprayed it in anyway

i know its not my thermostat

but when it overheats i feel the top hose and its hot and the bottom is cold

somebody have the majic answer please

the first thing i said was thta i did a leakdown test and all 4 were at 0%
also i can have the car run with the rad cap off and no bubbles.
so like i said earlier its obviously not headgaskets

i can sit at idle all day and it won;t overheat
if i accelerate from a light too much it will start to go hot
but if i go easy on the throttle it will ease down

i think it might be a radiator flow issue
i hosed it out before and no crap came out
and it seemed to come out ok

maybe i should rod it out anyway

does anybody know of a gauge you can put in line in your radiator hose to measure gpm of coolant flow?

or any other ideas (please read the previous posts)

I doubt it's a headgasket, unless there is water in the oil or vice versa or the car is putting out a lot of white smoke from the exhaust.

I had a similar problem on a car I just sold (it was a sr20 240). The coolant in the overflow reservoir would be boiling after just a short drive.

I changed the thermostat and gasket and thought I had fixed it. It didn't run hot for the first couple times I drove it. But, then after a longer more strenuous drive it did it again. My top hose was hot as hell, but the bottom one was cool to the touch.

After inspecting the bottom hose for a while I finally saw that there was a slight kink in it. It was just enough to obstruct some of the flow and cause the running hot problem. I trimmed the hose at one end to get rid of the kink and that took care of it.


Now, on my other car, a 95L with a usdm motor, I thought it was running hot when we first got it going, based on the factory temp. gauge. It turned out that the gauge was wired wrong during the swap. It sounds like to me that your waterpump isn't circulating the coolant since your bottom radiator hose is cold.
Here is what I'd do, if someone has already suggested this I apologize, I just skimmed the thread:
I'd check the lower radiator hose for kinks. I'd put a stock thermostat in it, let it heat up with the radiator cap off at idle and turn the heat on. Keep an eye on your temperature gauge. If you have a meat thermometer, stick it in where you took the cap off to monitor the temp as well. If you can do this without losing fingers, feel the hoses as it's heating up.

If that bottom hose stays cold and the car starts to overheat with the radiator cap off, then personally I would replace the water pump.

When you say it will sit and idle all day without overheating was that with the stock thermostat in? or after you took it out? I mean it could be a combination of things and if you've changed something....ya know it can get confusing.

Cam

It could also be a heat related exaust leak, try doing a leak down test with the engine hot. failing that you could have a clogged radiator, deposits build up in your rad over time and the only way to fix it really is a new radiator. if your radiator fills somewhat slowly (ie you have to stop pouring every few seconds to let it catch up) you mayhave a clogged rad. also cheak between the rad and the AC condenser (assumeing you have one) for leaves, twigs, and other debries that may be blocking airflow.

well the bottom hose is free of kinks and the bottom hose will be cold with the stock jdm thermostat in

i don;t have a condenser, AC is for chumps

i drove to jacksonville (150 miles)at night the other day and both there and back it didn;t overheat

the heat would rise however when i would nail it. then i would let off and resume cruising and it would go back to normal.

this is also with a RA tranny so my revs on the highway are near 4k

no coolant/oil cross contamination either

i think it is a flow issue, maybe i will get the radiator rodded, $80

i turned on the road and cruised for 1/4 mile and then ripped up this hill and i was listening to the boost (8 psi) and then i heard a pop and a big boost leak and then i smelled coolant.

later i found the top mount inlet pipe blown off the compressor outlet
and a coolant hose that popped off near the throttle body

wondering if the days events could be connected to or caused by past problems