Jump to content
SAU Community

Engine Temp Creeping

Gareth87

By Gareth87,
in Engines & Forced Induction

 Share

Recommended Posts

Gareth87 Community Regular

Gareth87

Posted
Posted

Hi everyone,

I've got an annoying problem with my FJ20. Ever since i did a full engine build on it, i have had temp creep issues at idle.

Its runs normally while driving at around 80-82 degrees with the thermos coming on at 82. However, it generally won't pull the engine temp back at idle. The fans will only just hold it at temperature or in traffic or a warm day, it will creep up slowly.

I run a 10 and 12 inch curved blade fans and a 3 core radiator which i have had completely stripped and rebuilt. (helped a little bit) The back of the bonnet is also lifted but i still find myself looking at the temp gauge creeping up slowly.

The fans don't run any shrouding so that will be something i will try to sort out and try.

Could anyone recommend anything else to try to help bring the temp down at idle?

Also, will a turbo beanie help? I run a big top mount turbo and gate and it pumps out some serious heat which is no doubt sending under bonnet temps sky high. but will this cause water temp to creep up?

Thanks in advance.

Gareth

Link to comment
https://www.sau.com.au/forums/topic/349426-engine-temp-creeping/
Share on other sites
Gareth87 Community Regular

Gareth87

Posted
  • Author
Posted

much bigger cams, head work, forged pistons, rods, external oil pump setup.

The only thing i think could make it temp creep to do with the engine would be the head work and bigger cams as its a fairly lumpy idle and idles around 1000 rpm.

Water pump was a new standard part.

Interesting you say lifting the bonnet makes things worse.. wouldn't that vent hot air?

paulr33 Grand Master

paulr33

Posted
Posted

no i believe the bonnet is setup like that and makes a pressure zone

i dont remember the physics behind it, but i think raising the bonnet makes it worse for temps

did you raise the bonnet at same time of engine rebuild?

blind_elk Grand Master

blind_elk

Posted
Posted

Raise the cut-in temp of the fans. There is no point fitting thermo fans that run basically all the time. All you are doing is shifting the load on the engine from a factory fan to the alternator. The cut-in can be as high as 90 C, or even higher - the motion of the car will control the engine temps; the fan is just for those times when the engine gets a bit hotter because the car isn't moving, or is moving too slowly.

As for the temp increasing at idle, are you sure the fans are running the right way - pulling air through the radiator into the engine bay (I'm assuming you have had to mount the fans on the engine side of the radiator).

Ordinarily, having a raised rear of bonnet is only a problem when the car is moving - there is a high pressure region created at the base of the windscreen (that's where comes from for the heater / a/c in the cabin). When the rear of the bonnet is raised, this high pressure region feeds a high pressure into the engine bay, and that restricts air flowing through the radiator to cool the engine. (you should recall from high school physics that air moves from regions of high pressure to regions of low pressure; if the inside of the engine bay is already at a high pressure, then air from in front of the radiator won't flow towards that region)

Kinks Grand Master

Kinks

Posted
Posted

shroud should make a massive difference. otherwise you're just circulating hot air around the engine bay not actually pulling it through the core.

raised bonnet may help *slightly* when stopped but when underway it will do nothing as the base of the windscreen is a high pressure area and you will not get any air being removed once you're moving. for best cooling when moving you need a sealed bonnet and your underbody plastic guards - these make a vacuum behind the radiator and help suck air through.

for cooling when stationary you need a powerful fan (engine driven, not electric) and proper shrouding. and a decent radiator which you've already got.

GTScotT Grand Master

GTScotT

Posted
Posted

From the mouth of one of NSW best known CAMS officials, raising the bonnet hinders cooling ability. As Paul said the windscreen is a high pressure zone and would alter the airflow through the engine bay while having it propped up.

This should be changed back to normal however I do not think this is the source of your problem. I believe you have airlock in your head (poorly bled). The other thing I have seen with alloy radiators are the tubes expanding and not letting any air through.. While they still flow fine they do jack all for cooling. I have generally seen cheap alloy rads to SUCK at cooling regardless.

Recommend swapping to stock radiator (for test) and being very careful while bleeding coolant. GL

Gareth87 Community Regular

Gareth87

Posted
  • Author
Posted

Thanks for all the replies everyone. It definitely seems as though i will drop the back of the bonnet back down. I did that recently to try but only seemed to delay the onset of temp creep while stationary. Did nothing while moving.

The radiator isn't alloy, its a standard radiator for the model car with an extra core and it's bled for certain.

The temp sits around 80 when driving but when stationary in traffic it will climb into the 90s and i have to keep moving for it to come back down. So to me it has to be an airflow issue i would have thought. I know its not huge temps but if i eft it to sit there... it would keep climbing.

The fans are on the engine side and like i said, with no shrouding, so i think dropping the bonnet and building a shroud will be a start.

Anything else??

Thanks for the input, some interesting points there.

FJdat Contributor

FJdat

Posted
Posted

like everyone else has said, the fan shroud should help.

Also check the timing at idle.. sometimes retarded timing at idle can cause the temp to rise at idle.

What CFM are the fans rated at?

Was the radiator cleaned and flushed after the engine was run in?

Gareth87 Community Regular

Gareth87

Posted
  • Author
Posted

Ok ill suss the timing.

The fans... i have no idea what CFM they flow. Cant find anything on them to tell me either.

Yes the radiator was cleaned and flushed after run in.

Has anyone found turbo beanies to reduce engine temp or creep?

G

  • 4 years later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • oHBoy.
      Starter motor replacment teeth count.

      By oHBoy. · Posted

      I had 3 counts over the last couple of weeks once where i got stranded at a jdm paint yard booking in some work. 2nd time was moving the car into the drive way for the inspection and the 3rd was during the inspection for the co2 leak test. Fix: 1st, car off for a hour and half disconnected battery 10mins 4th try car started 2nd, 5th try started 3rd, countless time starting disconnected battery dude was under the hood listening to the starting sequence fuel pump ect.   
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      This. As for your options - I suggest remote mounting the Nissan sensor further away on a length of steel tube. That tube to have a loop in it to handle vibration, etc etc. You will need to either put a tee and a bleed fitting near the sensor, or crack the fitting at the sensor to bleed it full of oil when you first set it up, otherwise you won't get the line filled. But this is a small problem. Just needs enough access to get it done.
    • suko
      J50 clock date suddenly reset to January 1

      By suko · Posted

      The time is always correct. Only the date is wrong. It currently thinks it is January 19. Tomorrow it will say it is January 20. The date and time are ( should be ! ) retrieved from the GPS navigation system.
    • MBS206
      Mistakes were made, my R34 Story

      By MBS206 · Posted

      Buy yourself a set of easy outs. See if they will get a good bite in and unthread it.   Very very lucky the whole sender didn't let go while on the track and cost you a motor!
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      Well GTSBoy, prepare yourself further. I did a track day with 1/2 a day prep on Friday, inpromptu. The good news is that I got home, and didn't drive the car into a wall. Everything seemed mostly okay. The car was even a little faster than it was last time. I also got to get some good datalog data too. I also noticed a tiny bit of knock which was (luckily?) recorded. All I know is the knock sensors got recalibrated.... and are notorious for false knock. So I don't know if they are too sensitive, not sensitive enough... or some other third option. But I reduced timing anyway. It wasn't every pull through the session either. Think along the lines of -1 degree of timing for say, three instances while at the top of 4th in a 20 minute all-hot-lap session. Unfortunately at the end of session 2... I noticed a little oil. I borrowed some jack stands and a jack and took a look under there, but as is often the case, messing around with it kinda half cleaned it up, it was not conclusive where it was coming from. I decided to give it another go and see how it was. The amount of oil was maybe one/two small drops. I did another 20 minute session and car went well, and I was just starting to get into it and not be terrified of driving on track. I pulled over and checked in the pits and saw this: This is where I called it, packed up and went home as I live ~20 min from the track with a VERY VERY CLOSE EYE on Oil Pressure on the way home. The volume wasn't much but you never know. I checked it today when I had my own space/tools/time to find out what was going on, wanted to clean it up, run the car and see if any of the fittings from around the oil filter were causing it. I have like.. 5 fittings there, so I suspected one was (hopefully?) the culprit. It became immediately apparent as soon as I looked around more closely. 795d266d-a034-4b8c-89c9-d83860f5d00a.mp4       This is the R34 GTT oil sender connected via an adapter to an oil cooler block I have installed which runs AN lines to my cooler (and back). There's also an oil temp sensor on top.  Just after that video, I attempted to unthread the sensor to see if it's loose/worn and it disintegrated in my hand. So yes. I am glad I noticed that oil because it would appear that complete and utter catastrophic engine failure was about 1 second of engine runtime away. I did try to drill the fitting out, and only succeeded in drilling the middle hole much larger and now there's a... smooth hole in there with what looks like a damn sleeve still incredibly tight in there. Not really sure how to proceed from here. My options: 1) Find someone who can remove the stuck fitting, and use a steel adapter so it won't fatigue? (Female BSPT for the R34 sender to 1/8NPT male - HARD to find). IF it isn't possible to remove - Buy a new block ($320) and have someone tap a new 1/8NPT in the top of it ($????) and hope the steel adapter works better. 2) Buy a new block and give up on the OEM pressure sender for the dash entirely, and use the supplied 1/8 NPT for the oil temp sender. Having the oil pressure read 0 in the dash with the warning lamp will give me a lot of anxiety driving around. I do have the actual GM sensor/sender working, but it needs OBD2 as a gauge. If I'm datalogging I don't actually have a readout of what the gauge is currently displaying. 3) Other? Find a new location for the OEM sender? Though I don't know of anywhere that will work. I also don't know if a steel adapter is actually functionally smart here. It's clearly leveraged itself through vibration of the motor and snapped in half. This doesn't seem like a setup a smart person would replicate given the weight of the OEM sender. Still pretty happy being lucky for once and seeing this at the absolute last moment before bye bye motor in a big way, even if an adapter is apparently 6 weeks+ delivery and I have no way to free the current stuck/potentially destroyed threads in the current oil block.
×
×
  • Create New...