Overheating 25det

[darkoh69]

Hey. A 10 month old ongoing overheating problem thats just pushed me close to breaking point.

33, S2, 322kw. Nistuned with all the usual mods an unopened engine would need for those numbers. Was tuned & went ballistic for about 12 months. Then about 10 months ago picked up a pinhole in the Chinese rad Id had it on there for a couple years & it was 2nd hand when I got it so I wasn’t surprised when it finally let go. Car got a little warm, not boiling but around 3/4 on the factory gauge. I wasn’t far from home so no problem I thought. I shopped around for a decent new rad I was targeting Mishmoto but at the time Covid supply chain issues & container ships stuck in Panama canal there was nothing decent in the country so I ended up getting another cheap Chinese one from redline performance with accompanying twin thermos. Chucked it in wired it up bled it out 1st drive & started warming up again so straight home. Thermostat I figured. So got a new 1 chucked it in & no change. Water pump I thought next. New one in still no change, sits at half on the gauge for 30-45 minutes no problem . As soon as I leave my driveway temperature starts going up. Needed a break from it so I parked it up for a couple of weeks. Next attempt I started her up & for about 10 seconds it was down on a cylinder then quickly came right, narrowed it down to cyl#4 only for a few seconds after the first startup after sit a few hours. Same time I noticed some tail pipe steam. So head gasket I thought. A few months later I got a Tomei 1.2 thick, arp2000 studs, all the other bits Id need & whipped the head off sent it to get tested dipped & skimmed. Bolted it all back together & today started it up bled the air out it sat & idled held running temp for 30-45 minutes as soon as I left my driveway the f**king c*nting sl*t started heating up again.

Any ideas anyone?

[Dose Pipe Sutututu]

Avoid eBay radiators, including the eBay ones sprayed Mishimoto on them.

Get a PWR or Koyo or so.

Also did you bleed the system properly?

[darkoh69]

I think so. Ffp dosnt have a bleed screw so I drive it up on ramps & thread tape an upside down coke bottle in top of rad. Idled till running temp heater on full gurgled a lump of air out once stat opens. 

[darkoh69]

17 minutes ago, Dose Pipe Sutututu said:

Avoid eBay radiators, including the eBay ones sprayed Mishimoto on them.

Get a PWR or Koyo or so.

Also did you bleed the system properly?

Do koyo flow water around & though the whole rad or does the water fall straight down from inlet to outlet?

[Duncan]

That's a "twin pass" radiator, there is a divider in the centre of the core forcing water to go to the other side before it can reach the exit. 

Much more expensive design, if a radiator has that it will say so

[robbo_rb180]

I'd say the biggest issue will be the 2 cheap fans on it that came with the radiator. Ditch them and get the factory clutch fan and shroud on. The cheap stuff doesn't move enough air.

The only electric fans worth putting on are either spal or maradyne. In 14 or 16 inch with proper shroud.

I use cheaper radiators but always use factory fan or the mentioned electric ones with no issues. 

[Duncan]

But, did I correctly understand.....it doesn't overheat idling and stationery? That is normally when a poor quality fan or fan install causes issues.

[darkoh69]

1 hour ago, Duncan said:

But, did I correctly understand.....it doesn't overheat idling and stationery? That is normally when a poor quality fan or fan install causes issues.

Yeah fine at idle.

[Dose Pipe Sutututu]

1 hour ago, robbo_rb180 said:

I'd say the biggest issue will be the 2 cheap fans on it that came with the radiator. Ditch them and get the factory clutch fan and shroud on. The cheap stuff doesn't move enough air.

Robbo's on the money here.

I missed the part where you're running the twin thermos. In the bin they go, factory shroud and fan then see how you go.

 

[darkoh69]

Yeah could be the fans. I was running a single 14 on my previous rad before this started happening with no issues ever. Infact the alloy radiator & that single 14 was the first mod I did to the car 7 or 8 years ago

[Milkmun]

Do you have a water temp gauge or consult cable to see the temps also? 

[Butters]

I'd be looking for constants between before and after the head gasket fix.

 

Given what you described which was quick to overheat once you start driving ? not extended drives ?

It sounds more than a fan / rad issue to me.

 

You could have the FFP leaking into chambers, also sad to say an issue with the block.   The cooling system could handle what ever small leak you have once you rev/drive it creates pressure and heat.

 

If you haven't already, pressure test your cooling system.

 

 

 

[darkoh69]

9 hours ago, Butters said:

I'd be looking for constants between before and after the head gasket fix.

 

Given what you described which was quick to overheat once you start driving ? not extended drives ?

It sounds more than a fan / rad issue to me.

 

You could have the FFP leaking into chambers, also sad to say an issue with the block.   The cooling system could handle what ever small leak you have once you rev/drive it creates pressure and heat.

 

If you haven't already, pressure test your cooling system.

 

 

 

Havnt been on an extended drive because Im sure it would keep getting hotter. Havnt pressure tested it yet but yeah I’ll have to. I was wondering about the plenum leaking coolant, could that cause the steamy tailpipe? Hopefully because Ive been trying to push the block issue to the back of my mind but the steam keeps bringing that thought right back to the front. The only thing that seems to have changed after doing the HG is the miss at startup, which I figured was from water seeping into #4 overnight & looking at the old gasket kind of confirmed it. Appreciate your input.

Appreciate everyones input

Edited October 16, 2022 by darkoh69
More info added

[darkoh69]

9 hours ago, Milkmun said:

Do you have a water temp gauge or consult cable to see the temps also? 

Only the factory gauge & the digital readout on the fan controller in the engine bay. Seen it a touch over 90 degrees C

Edited October 16, 2022 by darkoh69

[Duncan]

90 is certainly not dangerously hot, obviously you want temperature to be stable when idling and driving at low speeds but it would have to get much hotter to do any damage

[darkoh69]

Yeah as soon as I see the gauge on the dash start moving anything above halfway which it never usually would I nurse it back down my driveway. 

[Butters]

3 hours ago, darkoh69 said:

I was wondering about the plenum leaking coolant, could that cause the steamy tailpipe?

Very much yes.

 

Make sure you have all the hoses in the correct configuration too, I have seen people plumb coolant line into a vac line in these intake conversions before.

 

[darkoh69]

Plumping configuration should be ok I put the ffp on a few years ago & its been on the dyno twice since then. But when I was putting it back on after the head was back in I could have nicked the plenum to head gasket. It would be just my luck to fix a problem only to cause another problem with the same symptoms. Ive got a new aeroflow 14” fan coming today the twin 10s are really the only thing that’s different in my setup & probably the easiest job to check off the ‘possible cause’ list.

[Dose Pipe Sutututu]

no offense, but that Aeroflow 14" fan won't be moving much air either.

There's a reason why plenty of circuit racers with shit box Skylines (mine included, massive shit box) predominantly use the OEM shroud and OEM fan.

[darkoh69]

None taken. I hear what your saying. I know the clutch fans are good but unfortunately the blades on my fan bowed & chewed out the radiator not long after I got the car. So Ive had a 14 inch elec on an alloy rad ever since. It was all I could scrape together at the time & didn’t let me down for quite a few years. But when the old alloy did fail the only thing Ive put on there thats different is the twins. Pressure test has held 1.1 bar for 30 minutes now, is that enough pressure to test it with? What possible causes could that remove from the list?