2jz swap overheating help please!!
08-13-15, 01:34 PM
#1
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2jz swap overheating help please!!
I swapped a 2jzgte vvti auto into my 1995 lexus sc300. It has stock radiator and stock fan. the 2jzgte has stock twins that were rebuilt by driftmotion. at idle the temp needle sits perfectly in the middle in park. if i drive it or even rev the engine in park the temp gauge will rise to the 3/4 mark and as soon as i let off the gas the temp needle will drop. the needle is working properly because i used a infrared thermometer to test the temperature of the engine and waternecks and it got up to about 243 degrees fahrenheit. the temperature rises with the throttle so im expecting the head to be slightly warped. the headgasket was replaced by a shop and the block and head resurfaced. im afraid to blow my motor. is this common? it seems to me that exhaust gases are being pushed into the coolant causing the temp to rise and fall so fast. it has a new factory waterpump and thermostat. no leaks anywhere. virtually everything is either new or rebuilt. even going 70 on the highway the needle is still running about 3/4 value. any tips?
08-14-15, 10:21 PM
#2
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Have you tried burping the coolant system? There may be air in the coolant system that needs to be bled out. Another suggestion is to try running the car without the thermostat. Maybe the issue is with the thermostat not working properly or not fully opening.
08-18-15, 08:45 AM
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see this is what I was suspecting but the shop that did my rebuild swears the head and block were fine and that the headgasket was done right. Im suspecting its something in this area but I havent gotten the car back yet to run some tests on it. With the temperature rising under load and falling when decelerating really makes me think its a BHG/head/block issue. Ill keep yall posted I just didnt know if there was some other strange thing that could cause BHG symptoms.
08-18-15, 01:14 PM
#7
remember this thread Gerrb.
https://www.clublexus.com/forums/bui...ear-2-a-4.html
you may have a flipped headgasket, check for the tabs but you would also probably have oil in the coolant and coolant in the oil too.
how much did they deck the block? these are zero deck blocks normally if the block is messed up that means the motor is trashed pretty bad (Iron block w/ aluminum head), if they remove much material then the stock pistons will go past the block deck. normally its just the head that needs to be decked as the aluminum warps first but if the block is toast then grab a spare block.
https://www.clublexus.com/forums/bui...ear-2-a-4.html
you may have a flipped headgasket, check for the tabs but you would also probably have oil in the coolant and coolant in the oil too.
how much did they deck the block? these are zero deck blocks normally if the block is messed up that means the motor is trashed pretty bad (Iron block w/ aluminum head), if they remove much material then the stock pistons will go past the block deck. normally its just the head that needs to be decked as the aluminum warps first but if the block is toast then grab a spare block.
Last edited by Ali SC3; 08-18-15 at 01:19 PM.
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08-19-15, 04:18 AM
#11
OP, can you post a current engine bay picture here .
IF the picture I saw for your engine bay is current , in which you have damaged / broken fan blades and damaged or no fan shroud... then that will cause over heating when you put a load on that car. Is your fan clutch also in good shape ? Based on a picture I saw , looks like they damn rigged the SC300 propeller / fan blade to make it work on the GTE so it wouldn't hit the hose or anything.
Get the right GTE fan propeller , fan shroud and make sure you have a good fan clutch.
IF the picture I saw for your engine bay is current , in which you have damaged / broken fan blades and damaged or no fan shroud... then that will cause over heating when you put a load on that car. Is your fan clutch also in good shape ? Based on a picture I saw , looks like they damn rigged the SC300 propeller / fan blade to make it work on the GTE so it wouldn't hit the hose or anything.
Get the right GTE fan propeller , fan shroud and make sure you have a good fan clutch.
Last edited by gerrb; 08-19-15 at 04:23 AM.
08-19-15, 07:29 AM
#12
I dont think the fan shroud really matters....I drove my SC in stop and go city traffic without it on a 90 degree day and my needle never even moved....but I did buy the supra fan shroud and installed it.....makes the engine bay much cleaner with it installed...
Spend the money and get the Supra TT fan and Fan Shroud....
Also like others have mentioned check your oil and coolant.....
As far as the headgasket it should be installed like this.....the tab should be on the rear left of block...
Spend the money and get the Supra TT fan and Fan Shroud....
Also like others have mentioned check your oil and coolant.....
As far as the headgasket it should be installed like this.....the tab should be on the rear left of block...
08-19-15, 08:29 AM
#13
Ryan , try removing the fan shroud in +100 degrees Texas / Arizona or Southern state temperature and run your GTE hard for at least 30 minutes then go in a 5 miles per hour traffic situation for an hour and tell me that having a good shroud does not matter 
.
The only reason you are not overheating with 90degrees temperature is when you get to go and fresh air is pushed through the front . But in a bad traffic situation that barely moves and with a +100 degree southern temperature is totally different especially after a hard run. The fan shroud is there for a reason. It keeps the radiator / surrounding air within the radiator shielded from the engine temperature and the radiator fan being able to efficiently move the hot temp away from the radiator .
It is even worse in AZ ... +104 degrees , even in a freely moving situation where air is pushed from the front , many electric fans find it hard to cope up because the ambient air temperature to start with that is suppose to cool down the coolers (radiator / intercooler / AC condenser) is already hot. Many MKIV owners had to go back with the stock fan.
. The only reason you are not overheating with 90degrees temperature is when you get to go and fresh air is pushed through the front . But in a bad traffic situation that barely moves and with a +100 degree southern temperature is totally different especially after a hard run. The fan shroud is there for a reason. It keeps the radiator / surrounding air within the radiator shielded from the engine temperature and the radiator fan being able to efficiently move the hot temp away from the radiator .
It is even worse in AZ ... +104 degrees , even in a freely moving situation where air is pushed from the front , many electric fans find it hard to cope up because the ambient air temperature to start with that is suppose to cool down the coolers (radiator / intercooler / AC condenser) is already hot. Many MKIV owners had to go back with the stock fan.
Last edited by gerrb; 08-19-15 at 12:29 PM.
08-19-15, 11:03 AM
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its not the fan or fan shroud or fan clutch. I used is300 electric fans with a shroud just to make sure it had nothing to do with the air flow through the radiator and its the same story. quick overheating and quick temperature drop back to operating temperature. with about a half second of load on the engine the temperature gauge rises up to 3/4 and as soon as you let off the throttle it drops back to normal in less than a second. it seems to me the most logical reason is a BHG problem because of the hot exhaust gases in the coolant passage heating up the sensor quickly. the head was warped and got resurfaced but possibly it wasn't done right. also there is quite a bit of power loss. there is no coolant in the oil or oil in the coolant though.
08-19-15, 05:57 PM
#15
Without a doubt the stock fan is the best option......no matter what....
Not questioning the fan shroud just sharing my experience....fyi....the scenario that I mentioned above was after a hard drive....i.e full boost pulls ...non the less the shroud will help with keeping the air from the stock fan contained to the radiator
Not questioning the fan shroud just sharing my experience....fyi....the scenario that I mentioned above was after a hard drive....i.e full boost pulls ...non the less the shroud will help with keeping the air from the stock fan contained to the radiator