420A Coolant reservoir is bubbling after I park and turn the car off and I have a 420a with a turbo

[Giomyman11]

If anyone has any thoughts on this or why it’s doing this I live in Florida so it’s always hot. I have heat wrap on my downpipe and external wastegate but not any of my ac lines or coolant lines.

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[99dsmer4g63]

Does your car ever overheat? Coolant level okay?

If you’re overheating and adding coolant every so often that tells me she’s running hot/blown head gasket.

-Daniel

 

[pauleyman]

Have you checked the basics? Cap, thermostat, fans, coolant level. What temp is the car running?

 

[Giomyman11]

Does your car ever overheat? Coolant level okay?

If you’re overheating and adding coolant every so often that tells me she’s running hot/blown head gasket.

-Daniel

It’ll overheat sometimes if I’m stopped for a long time whenever I turn the ac on the temp will go up so I’m not sure if the ac has anything to do with it. I’m not adding coolant it’s just always bubbling if I’m pushing the car

 

[Giomyman11]

Have you checked the basics? Cap, thermostat, fans, coolant level. What temp is the car running?

My fans turn on we have it so they’re always on. I was thinking the cap but I’m not sure cause it’s new. The temp will run normal until I start to idle for to long

 

[pauleyman]

I would run a coolant pressure check and a leakdown test

 

[99dsmer4g63]

I agree on the leak down test. Confirm the health of the motor. Your cooling system may be operating the way it should but if the motor is unhealthy no amount of coolant bandaids is going to fix it.

We put a turbo on my dads 420a years back when it had 120k on the clock. He blew the head gasket within the first month. Only symptom was it was getting hot. Tested the coolant and it came back with exhaust fumes in it.

-Daniel

 

[Giomyman11]

I agree on the leak down test. Confirm the health of the motor. Your cooling system may be operating the way it should but if the motor is unhealthy no amount of coolant bandaids is going to fix it.

We put a turbo on my dads 420a years back when it had 120k on the clock. He blew the head gasket within the first month. Only symptom was it was getting hot. Tested the coolant and it came back with exhaust fumes in it.

-Daniel

We already rebuilt the motor not to long ago so it’s a brand new motor so there’s no way it could be head gasket. I already blew the motor before I rebuilt it so I know your dads pain on that

 

[BLACK'98DSM]

What kind of cooling fans are you using? I can see how slim they are. I understand that you probably do not have clearance to use the thick OEM fans, but do note that most if not all aftermarket fans will not push as much air as the OEM fans. Even with this being true I can't say that this alone would cause the coolant to boil, not since you have them set to constantly run. But it may play into this.

Also what did you use to bolt the head on when you rebuilt the engine? Did you use head studs, new head bolts, reuse the existing bolts? Head studs are recommended for a turbo engine since the higher cylinder pressures can actually stretch the head bolts and cause poor headgasket sealing. And reusing head bolts is the last thing you'd want to do since they're torque-to-yield (essentially meaning single use).

Try and diagnose a headgasket issue. After verifying good health of the headgasket I would try using a cooler thermostat. I want to say the stock thermostat was a 190 degree unit. Most replacements are 180 but you can buy as low as 160. If there really is no other issue besides cooling system limits then going cooler with the thermostat should help keep the temps down. I use a 160 degree thermostat in my NA build just because of how high I rev it. The stock cooling system is good but would have temp creep with extended red line use.

 

[99dsmer4g63]

We already rebuilt the motor not to long ago so it’s a brand new motor so there’s no way it could be head gasket. I already blew the motor before I rebuilt it so I know your dads pain on that

Just because the motor was rebuilt does not mean there is no way it could be the motor. It very well could be. Hopefully it isn’t but I wouldn’t rule it out.

A simple leak down test on the cylinders would confirm this

-Daniel

 

[CKOPOCT]

We already rebuilt the motor not to long ago so it’s a brand new motor so there’s no way it could be head gasket. I already blew the motor before I rebuilt it so I know your dads pain on that

It doesn't matter how careful and thorough one might be, there is always the chance that things go askew. A head gasket could be weak due to a manufacturing defect. The head might have gotten a scratch on it. A head bolt/nut might not have been torqued down enough. Crap happens to the best of us. Pretty sure every wrench and wiseman in here can relay a story of when the very common thought of "X is new so it can't be that" turned into a long and frustrating battle of checking the wrong things and chasing a ghost that turned out to be that flawless "perfectly new" part.

 

[Dericsh]

It doesn't matter how careful and thorough one might be, there is always the chance that things go askew. A head gasket could be weak due to a manufacturing defect. The head might have gotten a scratch on it. A head bolt/nut might not have been torqued down enough. Crap happens to the best of us. Pretty sure every wrench and wiseman in here can relay a story of when the very common thought of "X is new so it can't be that" turned into a long and frustrating battle of checking the wrong things and chasing a ghost that turned out to be that flawless "perfectly new" part.

Bringing up bad memories.

OP- put a coolant funnel on in place of the cap during your leak down test. Check for bubbles while the cylinders are pressurized.

Nice looking setup, BTW.

 

[Giomyman11]

I live in central Florida and I own a 1998 Eclipse RS. I have done a lot of mechanical and cosmetic work on this car but for now I am going to focus on this, last year I rebuild my 420a engine with forged parts (wiesco pistons, Eagle rods and arp head studs) and I installed a turbo kit from A3USA (t3-t4 turbo not sure of the size). See picture.
Also, I installed a brand new aluminum radiator, from Gen 1 that I outfit for my Gen 2, and new aftermarket fans. See picture.
The issue I been having is when I parked the car after a long drive my coolant reservoir fills quickly and starts boiling. When I am driving the car I have no issue with temperature unless I turned the air conditioner on and the temperature outside is on the 90s then I see my temp gauge slightly pass the center line however when I turned the air conditioner off the temp goes back to normal. When I drive at night with the air conditioner on I don’t have any issue with temperature trying to move up because is cooler.
Obviously, I have to much heat coming from the exhaust manifold, down pipe, turbo and waste gate. I have wrapped the down pipe, installed a turbo sock and cover the exhaust manifold with aluminum with fiberglass material (see picture) but I still have the issue during the day on the Florida Summer.
I thought about plugging the air conditioner lines and remove the condenser to allow more air flow thru the radiator but I wish this to be the last resort as having a car without air conditioner in Florida summer to be brutal.
I wanted to emphasize that on the colder months I don’t have any problems with temperature or boiling coolant when I parked.
Has anyone going thru the same problem? What was your solution?

P.S. I have replaced the radiator cap as well.

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[BLACK'98DSM]

The AC causes the temperature to rise because of the additional stress on the engine. That's why it had a separate fan from the factory, which is larger than the regular radiator fan.

At this point I would do as I previously suggested and install a colder thermostat. Check what yours is rated for first. It will be stamped into the metal.

Also note that you're using the stock dummy gauge. A slight amount above normal operating temperature could be a difference of 20 degrees. If it ever reaches the hot side there is a serious problem.

 

[CKOPOCT]

The first thing is to check and make sure everything is functioning properly. Compression and leakdown tests to ensure no internal issues. Cooling system pressure test to ensure the integrity of the water system. Rebleed the cooling system to ensure no trapped air at a high spot in the head. Make sure you don't have any exhaust leaks or anything that might cook the radiator or water lines. Check your logs or gauges to ensure you aren't running lean and therefore too hot. Make sure your fans are both spinning well and that they are sealed against the radiator. Pressure test the radiator cap, because pressure raises the boiling point of a liquid... so if the cap won't hold pressure the coolant will boil at a lower temp.

If all of that is done and your system is primo, then it's time to consider what steps to take.

Judging from the picture you have very little room for air to flow, and if can't flow well it can't cool well. You could consider changing hoods to add vents, giving more air flow out of the engine bay. You could also raise the back of the hood (by the hinges) to allow air to vent and escape above the firewall. Anything to increase air flow out of the engine bay.

One thing I would check is to see if there is any place in front of the radiator where air can go around the radiator instead of flowing through it. You may benefit from adding/improving the air dams to help capture and force more air to go through the fmic/condensor/radiator. Some of us have had to add flashing or other material to create an air tunnel between the fmic and the radiator to ensure air doesn't escape off to the side.

You could check the coolant mix level as well. Being in S. Florida you don't need as strong a coolant/water ratio; water dissipates heat more efficiently than coolant. Just be aware that the coolant does a lot more than just keep the water from freezing and boiling. Coolant also has lubricating and anti-rust properties to it, so don't adjust the ratio too much. But making it a 40/60 or 35/65 mix might help. Watch out though because dropping the coolant ratio also lowers the boiling point of the mix.

You can add a product like Water Wetter to your coolant. I've used it and it has brought the coolant temps down a few degrees. Not a solution, but it may help a little.

 

[Giomyman11]

The first thing is to check and make sure everything is functioning properly. Compression and leakdown tests to ensure no internal issues. Cooling system pressure test to ensure the integrity of the water system. Rebleed the cooling system to ensure no trapped air at a high spot in the head. Make sure you don't have any exhaust leaks or anything that might cook the radiator or water lines. Check your logs or gauges to ensure you aren't running lean and therefore too hot. Make sure your fans are both spinning well and that they are sealed against the radiator. Pressure test the radiator cap, because pressure raises the boiling point of a liquid... so if the cap won't hold pressure the coolant will boil at a lower temp.

If all of that is done and your system is primo, then it's time to consider what steps to take.

Judging from the picture you have very little room for air to flow, and if can't flow well it can't cool well. You could consider changing hoods to add vents, giving more air flow out of the engine bay. You could also raise the back of the hood (by the hinges) to allow air to vent and escape above the firewall. Anything to increase air flow out of the engine bay.

One thing I would check is to see if there is any place in front of the radiator where air can go around the radiator instead of flowing through it. You may benefit from adding/improving the air dams to help capture and force more air to go through the fmic/condensor/radiator. Some of us have had to add flashing or other material to create an air tunnel between the fmic and the radiator to ensure air doesn't escape off to the side.

You could check the coolant mix level as well. Being in S. Florida you don't need as strong a coolant/water ratio; water dissipates heat more efficiently than coolant. Just be aware that the coolant does a lot more than just keep the water from freezing and boiling. Coolant also has lubricating and anti-rust properties to it, so don't adjust the ratio too much. But making it a 40/60 or 35/65 mix might help. Watch out though because dropping the coolant ratio also lowers the boiling point of the mix.

You can add a product like Water Wetter to your coolant. I've used it and it has brought the coolant temps down a few degrees. Not a solution, but it may help a little.

I’ll consider everything you said and try out all of your solutions and hopefully one of them will be the one that fixes it

 

[VelocitàPaola]

Is the turbo water cooled? I don't see coolant lines, but that could be adding a ton of heat to your cooling system.

 

[chrisman287]

Try to seal the rad cap better.

https://www.dsmtuners.com/threads/coolant-cap-seal-hack.510206/

 

[BLACK'98DSM]

I've had best luck with just using an old fashioned "safety" radiator cap. They do seem to seal better than the shitty replacements, contrary to what some believe. Gates makes them and sold on RockAuto. I went through a few MotoRad standard caps before going with this one and it's great. I like the ability to slowly purge pressure as well, if you need to open the system hot. Anything to make it seal is fine, but seems odd to modify a shitty cap when you could just buy a good one.

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