Need to figure out heat issue.

[FastFwd]

So basically i rebuilt the motor not long ago then got it tuned etc etc. All was running find until one 35 degree day around 4 weeks ago the motor temp got upto around 99 degree's. Since then ive flushed the motor used anti freeze installed a new mugen thermostat and since then its been better but somethings not right. The motors lost a little torque, boost doesnt hold properly, The engine heats really quickly then stops at 77 and slowly rizes to 85 for drives over 20 mins, i can smell coolant occasionally in the cabin.

Can you guys help me out. I've never blown a head gasket before so im not to sure what the symptoms are. I've been told if you blow one the coolant should bubble from the radiator but its not.

Few things: ive got a fairly new Thick koyo radiator and i have my fan switch set to ACC so its always on, running that new mugen thermostat and new coolant.

Otherwise the car is find to drive unless u really hitting boost then u can feel lack of power and boost doesnt hit 10psi unless you really drop it back a gear and give it sh1t. Also i cant drive the car on days hotter than 32ish for more than 15 mins or else it can reach into the 90's

help would be much appreciated.

[Limbo]

run the car with the radiator cap off. rev the car & see if you can see bubbles forming
Also check oil for milky stuff, or change in colour of the coolant
That's a start.

The most certain way is to get a test done at a radiator place. They use this chemical and put it on the radiator cap, and the chemical changes colour if it sees any exhuast fumes, then u know for sure if there is a head gasket problem.

[wAYzoR]

^^ Great info.. just keep in mind tho if it is a blown head gasket, doesn't always pop the gasket between water and oil gallarys tho it is more common, it can also blow the little bit of gasket between cylinders..

Do you know the specs of your thermostat and have u test drove it without one? and is the motor idling smoothly?

[Cooker]

Very important, did you bleed the coolant system?

90's is fine, OEM honda fan doesn't kick in till around 98. Hondas run hot. The coolant is pretty much bubbling when the fan comes on. It shouldn't go past 98 though. As soon as the fan cuts in it should drop dramatically.
If yours is going to 99 and the fan is on constantly then there is defiantly an issue.
Bleed it properly then do a pressure check.

[2MPRS]

open ur radiator cap and turn on ur car if it sprays coolant its a gasket

[bennjamin]

looks like the excessive heat may have split or deformed your heater core pipe (inlet or outlet) check that out

[FastFwd]

^^ Great info.. just keep in mind tho if it is a blown head gasket, doesn't always pop the gasket between water and oil gallarys tho it is more common, it can also blow the little bit of gasket between cylinders..

Do you know the specs of your thermostat and have u test drove it without one? and is the motor idling smoothly?

as i said its a mugen thermostat - so it opens at 75 degree's.


Very important, did you bleed the coolant system?

90's is fine, OEM honda fan doesn't kick in till around 98. Hondas run hot. The coolant is pretty much bubbling when the fan comes on. It shouldn't go past 98 though. As soon as the fan cuts in it should drop dramatically.
If yours is going to 99 and the fan is on constantly then there is defiantly an issue.
Bleed it properly then do a pressure check.

As i said my fan is hooked up to my ACC so its on all the time. I dont have it set to a switch like stock. plus 90's isnt fine...


open ur radiator cap and turn on ur car if it sprays coolant its a gasket

Sprays out :) k ill watch out for those sprays. Two things, your radiator builds up steam so it will spray out no matter what when its hot secondly when the head gaskets blown it will more likely bubble not spray. But i know what your getting at thanks :)


looks like the excessive heat may have split or deformed your heater core pipe (inlet or outlet) check that out

Yeh honestly i dont think its a head gasket as the drop in psi might be a different issue which is causing the bad torque, im just trying to sorta out this heat problem first but i dont want to rule out the gasket.

So this heater core pipe? is this the one that runs around the back of the block outside? and its metal? or do you just mean the main water lines? which comes from the block to the radiator

[JAP-S2K]

Sounds like a stuck thermostat. Regardless it being new, it can still happen. As it's only getting hot when your spanking it, yeah? Therefore it's a sounds like a flow issue. It doesn't have to be stuck fully shut, but if it's only open partially for this to happen. Or the thermostat could be installed back to front.

[Cooker]

As i said my fan is hooked up to my ACC so its on all the time. I dont have it set to a switch like stock. plus 90's isnt fine...

I understood that, thats why I said if yours if getting to 99 and your fan is on constantly then there obviously is an issue.
90's is fine, you think Honda just pulled a figure (98) out of a hat when they decided at what temp to make the fan come on??????

Hondas run best when in the upper temp regions. Mine makes max power at 94-96degrees.

You reckon 90's is hot hahaha
Some of the new Audi's don't engage the fan till 105degrees!!!!!!

The whole idea behind a cars cooling system is to maintain the vehicle at its optimum operating temp and every engine's optimum temp is differant. Honda B series optimum temp is between 90-96, 98 is when the temp starts to ruin the engines efficiency, thats why the fan comes on at 98.

Those low temp thermostats and fan switches are a load of crap, they are essentially making your engine to never/or take alot longer to reach its optimum working temp.

[FastFwd]

Sounds like a stuck thermostat. Regardless it being new, it can still happen. As it's only getting hot when your spanking it, yeah? Therefore it's a sounds like a flow issue. It doesn't have to be stuck fully shut, but if it's only open partially for this to happen. Or the thermostat could be installed back to front.

Nah its not stuck...i ran a test on my old OEM on and it opens at 88 degree's when it should be around 85 but thats ok. I did the whole boil the water over the stove trick. and i did it with my new Mugen one just to be safe and 75 on the dot it opened up so its not the thermostat. And its not installed back to front, i dont think you can do that on B series as they have two little grommets for the seal to sit on or else it wont bolt up properly.


I understood that, thats why I said if yours if getting to 99 and your fan is on constantly then there obviously is an issue.
90's is fine, you think Honda just pulled a figure (98) out of a hat when they decided at what temp to make the fan come on??????

Hondas run best when in the upper temp regions. Mine makes max power at 94-96degrees.

You reckon 90's is hot hahaha
Some of the new Audi's don't engage the fan till 105degrees!!!!!!

The whole idea behind a cars cooling system is to maintain the vehicle at its optimum operating temp and every engine's optimum temp is differant. Honda B series optimum temp is between 90-96, 98 is when the temp starts to ruin the engines efficiency, thats why the fan comes on at 98.

Those low temp thermostats and fan switches are a load of crap, they are essentially making your engine to never/or take alot longer to reach its optimum working temp.

To be honest I've said that honda's run hot before but alot of people on here think 80's is where the B series should be running at. mines always ran in the 80's with my old stock radiator it would reach into the 90's with my turbo setup but after i got the koyo radiator it fixed that. Im just worried now that this small overheating issue that is intermittent is also causing less torque issue. I dont know if they are related yet but small signs like smelling coolant etc is just getting me worried.

Yeh when i went to buy a new thermostat i was going to get the OEM one again but for the same price you can get mugen which opens up a little lower which i need cos im going to be running high boost. But ive also been told that oem has better flow. so its loose loose win win really.