Help diagnose cooling problem

[mob]

Hey guys, a couple weeks ago my car was missing around 2500 rpm and I had coolant on top of my timing cover, but it wasn't overheating, unless of course I lost enough coolant. But anyways I changed my intake gaskets. Then I changed the fuel pump, but that's another story. So I got my car running yesterday and when I'm driving it starts over heating reallll bad, it'll go all the way up and stop about one bar before the red, and come down when I come to a stop or slow down, but still stays high. Well I was hoping that after the intake more coolant had to flow through the engine and I just needed more. So I took the cap off let the engine run and added coolant. When it got to the top I noticed it was bubbling a little. So after work I got home and it overheated again so I looked at my engine in the driveway and there was coolant dripping down my water outlet neck from my top rad hose. I thought this was weird because I changed the radiator hose and clamp when I did the gasket. So today I tightened up the hose, and went to check the coolant and it was low again. So I turned the car on and filled it up. When the coolant was at the top, a nice size bubble would come up every two seconds, this is when the engine is completely cold. And when I started it up, it wouldn't stay started I had to hold the gas for 5 minutes or else it turned off, finally got it to run with a little bit of a surge, then evened out. Also when I'm driving and push in the clutch or go in neutral the rpms go down but stop at 1200 and stay there till I stop then go down to about 800.

I did a vacuum check and its at 12 inches on the dot at idle from the fpr vacuum. Because of the fact the car wasn't giving me head gasket problems before the intake install, I think I can rule that out. But if it was the intake gasket wouldn't the car running rough be vacuum related? Is it possible my vacuum is fine at idle but im losing it at higher rpms? Anyone know how many inches I should look for when revving a little? Got a bcam

I have a new water pump and t-stat I could install but I dont think thats my problem, I think my over heating problem is due to the air in the system and I think it was coming out of my top rad hose because it had so much pressure and was trying to escape, correct?

 

[Lawbreaker5.0]

if your heat works=blows real hot, than there are no bubbles in the system.

 

[mob]

what do you mean? I can see bubbles in my system. And I dont have a heater core, my heat doesnt work.

 

[Lawbreaker5.0]

what do you mean? I can see bubbles in my system. And I dont have a heater core, my heat doesnt work.

oh well if you don't have heat than that test won't work.

Have you pressure tested it to make sure you don't have any more leaks? THe pressure should hold steady

 

[mob]

No havent done that yet. Will a pressure test pin point where air is getting into the system though?

 

[Lawbreaker5.0]

No havent done that yet. Will a pressure test pin point where air is getting into the system though?

i don't think it will tell you where air is coming into the sytem, but if you have a leak it tell you where that is. You need to verify you don't have a leak then determine if you still have an air bubble in the system. go rent one from the autozone sinces its free, (pay deposit, use it and return it and get deposit back).

edit: its always a good idea to replace a thermostat when you over heat your car, so since you were pretty close to over heating and u have one i would throw it on, but i hate taking off the little hose running to the waterpump. its a biach

 

[Foxfan88]

take the cap off. get a jack and jack up the front end of the car as high as you can. the goal is to get the radiator cap to be the higest point in the cooling system.

then fire the car up and let it warm up, keep the level up to the top of the radiator.

if you have a big air pocket (chances are there is since you had the intake off and etc) then the coolant will fall quickly when the Tstat opens.

if there is a big enough air pocket, coolant cant reach the T stat. to open it, so the coolant just sits in the block and gets hotter and hotter.

anyways try that.

and what temps are you seeing when "overheating"?

some people consider 210 overheating, which is NOT the case, i wouldnt be worried until you see temps in 240+ range, thats getting pretty warm....

reason i say that is i tried burping the system on my car a long time ago and i saw the coolant temps get real high, i would freak out and shut the car off, but if i would have just waited like 5more secs, there was a huge air pocket that came out.
if no luck then, you can try taking the coolant temp probe for the stock gauge out and manually fill the engine with coolant from there, then try again.

 

[mob]

Well I borrowed a pressure tester from my work so im going to do that. I am going off the stock temp gauge but it is going all the way up, right up to the last red bar. This is within a couple miles of driving.

Fox fan Im a little confused by that test. I understand jack the car up so the radiator is the highest point and run it. But what am I looking for? Is this supposed to take the air pocket out if there is one?

If there is a big air pocket could that make the car run a little funky, like it has a vacuum leak? And should I lift the car up and run it BEFORE I do the pressure test?

 

[Lawbreaker5.0]

Well I borrowed a pressure tester from my work so im going to do that. I am going off the stock temp gauge but it is going all the way up, right up to the last red bar. This is within a couple miles of driving.

Fox fan Im a little confused by that test. I understand jack the car up so the radiator is the highest point and run it. But what am I looking for? Is this supposed to take the air pocket out if there is one?

If there is a big air pocket could that make the car run a little funky, like it has a vacuum leak? And should I lift the car up and run it BEFORE I do the pressure test?

thats a trick to get the air bubble out.

An air pocket won't make the car run like a vacuum leak, it'll just make it run hot

But, if you let it get hot enough (close to the red) than i could see it sounding worse, driving worse, etc etc...

pressure test the car first, then try to take the bubble out.

on a side note: i've never really had trouble with air bubbles (pockets of air) in the system, they usually work themselves out.

 

[mob]

Well I pressure tested the car today and it held 16psi no problem so that means theres no leak and its probably just an air pocket right? I tested the cap also but it didnt hold pressure, I think the tester cap I had was the wrong one though, I am going to get a new cap anyways because those vent ones suck nuts.

I lifted the car up on jacks, I was worried because it looked like my upper radiator was higher than the cap but I ran it anyways. There were no bubbles for about 5 minutes, I left it running, then the bubbles started showing up it was like non stop bubbles for a couple minutes. Then the tempature gauge shot up to about half way on the stock gauge which isnt bad so I wasnt too worried. Then the coolant just started shooting out, it was bubbling out but it was like throwing up. Once that was over the coolant level went way down in the radiator but the tempature gauge went down and stayed down. I left it running for like 5 more minutes, the coolant level started rising and was pouring out coolant, but it wasent shooting out, or bubbling out it was just like overflowing, but it didnt get hot again. I turned it off so I didnt lose all my coolant. Does this sound normal? I thought the overflowing was maybe because the coolant was hot and was running through the system better without the air bubble? Or am I just making up theorys and theres still air in there? Thanks Foxfan for the tip. I may just take it for a spin and see if it gets hot.

 

[mob]

God dammit, well I drove it around just now, and it overheated again to 270 within 1 minute of driving. And it started sputtering at around 4krpm. I dont know what else to do. It looks like it built so much pressure that my overflow tank overflowed and started pouring out coolant, because there was smoking coolant all over my radiator and my overflow tank was full. Why is it building so much pressure? Could this have anything to do with a bad cap?

EDIT: I've been doing a lot of searching and it sounds like its the tstat or cap. I even found one of my old threads where I had almost this same problem I had just forgot, and all I did was change the tstat. So Im going to do that tomorrow and hope it works. Keep my fingers crossed. Also gonna do a compression check to rule out the heads.

 

[Lawbreaker5.0]

do you feel coolant flowing through the top rad hose?

i kinda think its a thermostat too.

When you put the new one in make sure the weep hole is facing up if it has one.

 

[phutch11]

You sure you've got t-stat in the right way? I hate to admit it, but I've put them in backwards and gotten exaclty the same symptoms.

Good luck...

Posted via Mobile Device

 

[mob]

Yea its in the right way, Its been in there for about a year, I never took off the water outlet when I did the intake swap. I havent done this in a year or so, should I put RTV on both sides of the water outlet gasket? I remember when I first did it, it started leaking, I had to take it off and put rtv around it.

 

[Lawbreaker5.0]

Yea its in the right way, Its been in there for about a year, I never took off the water outlet when I did the intake swap. I havent done this in a year or so, should I put RTV on both sides of the water outlet gasket? I remember when I first did it, it started leaking, I had to take it off and put rtv around it.

i've never put any rtv on any side, but it wouldn't hurt. just a light smooth coat. just make sure to clean both sides of the intake. I use a sanding stone that really works well. it takes off everything and leaves a new fresh finish.

 

[66sprint6]

please keep us posted on what happens. Im havin the same problem on the new(er) motor i put in the coupe. Ill admit at one point along the road of coolant woahs I put a new thermostat in backwards lol. I got it now runnin at about 210* all the time and she runs good but the heater is pretty lame and I swear there is still a bubble, but when I try to burp it out, it does like you said, the level will drop, ill fill it while its down and then it will GYSER out of the radiator LOL...what the heck??? I finally got her to run well enough and said screw it, im done.
Matt

 

[Foxfan88]

if you get big air pocket out with the car jacked up, you usually have to fill it back up and it shouldnt come spewing back out. could be a thermostat issue.

i would try taking the coolant temp sender unit out of the intake, the one on the driver's side front with the single wire connected to it.

pull that out and pour coolant in that hole. that should make sure that your getting coolant into the engine. once your confident your engine is pretty full of coolant BEHIND the T-stat. then try again. if no more luck. then i would try replacing the thermostat.

did this issue just come about out of the blue or did you change something??
you mentioned you had the lower intake off? thats a good way to get a nice big air pocket in the system. but usually they arent this hard to get out.

if you try and burp it again, put the cap on before you shut the car off. once you get the majority of the air out, just put the cap on and drive the car around, if its not getting hot then thats good then park it and let it cool off. then pop the cap back off. if the coolant level dropped some then the flowing coolant may have carried some more air into the radiator while you were driving.

 

[mob]

This issue started right after I put my lower intake back on. I didnt take off the water outlet when I took off the intake so maybe with spraying stuff on the intake to clean it up the thermostat went bad. I have no idea why the tstat would go bad right when I did the intake swap. Im gonna do a compression test tomorrow also to rule out the head gaskets.

If I pour coolant in the coolant temp sender and the tstat is bad anyways its not gonna help right?

The thing that confuses me a little was when I lift up the car and wait for the air pocket to come out im pretty much waiting for the tstat to open right? So, since after like 5-10 minutes it started shooting out coolant, doesn't that mean the tstat opened up? And if it opened up that means thats not my problem right? Why the coolant level went down then came back up and started pouring out coolant is beyond me though.

 

[Foxfan88]

yeah, your waiting for the tstat to open up. jacking the car up just simply puts the radiator cap as high as you can get it, in hopes to get the air pockets to get there easier.

once your air pockets get into the radiator they just simple go to the top.

if the engine has too much air in it, the coolant may not be able to get to the Tstat to even open it. so your T stat will stay shut.
if you pour coolant into the pipe hole in the lower intake, you fill the engine up behind the T stat, you should be able to get it pretty much full there. as you pour, the air will escape out the hole.

and yeah it makes no sense for the Tstat to go back from just an intake swap.

as for the spewing. ive burped my system a few times after having the intake or heads off ( engine completely empty of coolant.)

and i had the engine spew QUITE a bit of coolant up. i would see pretty warms ECTs and the spewing coolant and freak out and shut the car off ruining what i had just done.

try it again with the car jacked up. and let it just puke out coolant all it wants, helps to have a catch pan to catch it and dump it right back in. the only reason i can see for all the spewing is its trying to get a large air pocket out. just dont freak out, let it puke, once the coolant level drops ALOT, add water, just keep the radiator full. if it pukes let it.... if you really want to get the air out, let the car run for 15-20 mins.

sometimes revving the engine up will help get the air out.

if you ran a pressure check on the cooling system and it turned out good i doubt your HGs are leaking, seeing how you did do anything to cause them to go bad that i know of.

 

[mob]

Gotcha. I have a question, am I suposed to leave the pressure check on for like ten minutes? I only left it on for like a minute or two. Should I do it again?

When I change the tstat is there a chance I can get air back in the system again? Should I change the tstat and then lift the car up again and let spew coolant till its done?

The reason I turned the car off when it started pouring was because it wasent bubbling out anymore, it was just like overflowing, not spurting out.