crossbar17

what would make the coolant boil in my overflow tank?? i pwna 1988 rx7 SE NA and i have never ahd it do this,,,
a little info, my filler neck is broken on the top where the overflow hose goes to the overflow tank, (this is the littl e nub on tyhe top side of the radiator neck) is this causing my problem, or is it somehting with the cooling system, i am getting the engine block flushed out and the radiator replaced with a better higher flow one.


~Cole

jasonred3rdgen

possible engine rebuild because of water jacket o-ring leak. exhaust may be getting into the coolant and then the overflow tank. does it smell like exhaust?

crossbar17

so if the coolant in the radiator or the overflow tank smells of exhaust its the problem and i need a redbuild, how much does a rebuild kit cost?? where would i go to buy it i am a dealer

hypntyz7

crossbar...try this. With the car cold, open the filler cap. Fill it as far as you can with coolant. Leave the cap off. Now, find the fusebox under the hood. PUllout the 2 fuses closest to the engine. This disables fuel and spark so the engine wont run.

Crank her over, watching the coolant hole. Water should NOT gush out of the hole, maybe a little side spillage, but if it shoots up tot he hood, youre engine is shot.IF not, you have a small external problem such as leak, water pump, radiator, thermostat, etc.

As for a rebuild, parts cost about $700+, and labor is double that. I do rebuilds myself for around $1200 per engine, plus installation.

crossbar17

i will try this and tell you what happens

thanx

crossbar17

thats awesome i did the test, took out those fuses filled her up with coolant and turned her over, no spillage at all, coolant didnt even budge

~Cole

thanx much!!

Judge Ito

Hi crossbar. the most common problem for boiling coolant is when combustion starts to leak into your coolant system from a bad seal. there are many other reasons too. I find a very easy way to check for combustion leaking into your coolant. They sell a tester so u could check if there is co2 in your coolant system. the tester is about $45.oo and is very accurate. if u would like to go this way, just let me know and ill post more info. on it. This way if u don't have co2 present in your coolant system u dont not have to stress. And most likely u might have a bad fan clutch, radiator clogged and down the list.. take care...

oohotcarameloo

i have the same exact problem as crossbar urrrrgggggggg!!!!!!!!

jasonred3rdgen

you can also check for a leak by using a coolant system pressure checker. you remove the radiator cap, put the tester on in place of the cap, pump it up to system pressure and let it sit. if it holds the pressure you don't have a leak.

hypntyz7

Ok guys, I think we've established that he does not hav bad water seals. HE needs to concentrate on findin ghte leak/problem...common ones:

plastic trim under each radiator cap leaks
bad thermostat-replace with mazda unit
water pump weep hole, underneath
alternator/airpump belts tooloose, water pump slipping'
driver side heater core hose leaking(goes down and into block)
small hoses to throttle body leaking(especially the one that goes behind, down, and into the block)
bad fan...check for resistance to turning when hot.
lack of fan shroud, platic trim that directs airflow, etc.
leaking radiator(the plastic trim at top tends to seperate or crack)
clogged radiator
leak behind water pump housing at block(hard to find and see)
coolant not completely full...air pockets need to be bled.

Crossbar, if you have any questions feel free to ask. Also a better description of the problem would help.
Whatever you do, do NOT let it go above 3/4 hot EVER, or you WILL have a bad engine.

cymfc3s

if your engine does this cold while cranking, you might need a new motor:

hypntyz7

Yup, youre absolutely right about that. Damn, thats a bad case of it too! Look at all those rx7s...2 2nd gens and 2 3rd gens.

As long as your engine doesnt shoot out water when cranking you're ok as far as the engine. YOu just have an external leak or blockage, something causing water not to flow properly(including air in/getting into the system).

Green

is it pure coolant? or did you mix in water? When I had a BAD coolant leak in my seven, I would fill it with water before I went to work.. and it eventually had too much water in and not enough coolant, which caused it to boil.. NOT cool..

Make sure you have just coolant in there..

just a thought..

If a seven is running MEGA rich, would that cause engine temp to uped a considerable amount?

cymfc3s

and a 323 gtx squeezed in at the end =]


and to comment on the post by Green, made a good point that if you have too much water and not enought coolant it will boil over. Yes, water does cool better than anti-freeze, but it has a lower boiling point.
And running rich will not cause the motor to run excessively hot.

ReZ311

iTrader: (4)

wow. I never thought of doing it that way... You guys are geniouses! I learn something everytime I go to this board.

Poindexter10thae

iTrader: (2)

One more thing you guys. It is also pertinent to know WHEN the coolant is boiling. At start up, while running, or after the engine is shut off after driving. I had this same problem with my daily driver, as soon as I turned the car off the overflow bottle would boil and the cap would pop off and spew steam. This was caused by not having enough airflow in my case. I had a clogged/bad radiator and my fan clutch was completely freewheeling. Recently I found my heater hoses were leaking as well, might wanna check that out too.