What could the problem be?

Canuckrz · 07-06-2008, 08:30 AM

Quote:

Originally Posted by CyFi6

The fact that you are overheating is something you need to look into. You say the overflow tank has coolant in it to the full line. Does is your radiator full? Does the overflow tank spit out coolant ever?

Yes the rad is full and I've never noticed coolant coming out of the overflow tank.

Busted Knuckles · 07-06-2008, 12:59 PM

I agree with the previous post that questioned the amount of blow-by to oil pressure fluctuations. My oil pressure drops at idle, and picks-up at driving, but this has to do with worn bearings, not excessive blow-by. I don't have excessive blow-by. And yes, I tested it.

As far as the cooling system problems, you may want to flush and fill the cooling system, and make sure you pull the radiator out and flush it completely. Crap, gunk and rusty scale could be blocking some of the tubes in the radiator, cutting it's efficiency. Replace the cap and thermostat. Fill with 50/50 coolant. Toyota red is best. Anything good for aluminum protection is OK. I use distilled water. Tap water can contain chemicals that may shorten the life of the anti-rust and water pump lubricating additives in the coolant.

Of course, this is if you rule out a need to re-build. That should be the first focus. If the turbo is leaking oil, it will get sucked through the intercooler on it's way to the engine. You should see oil in the piping. If that is OK, a leak-down test will reveal the condition of the valves and rings. Any shop should be able to do this. If it is out of spec, a rebuild will be required.

SideWinderGX · 07-08-2008, 01:16 AM

Quote:

Originally Posted by Busted Knuckles

I agree with the previous post that questioned the amount of blow-by to oil pressure fluctuations. My oil pressure drops at idle, and picks-up at driving, but this has to do with worn bearings, not excessive blow-by. I don't have excessive blow-by. And yes, I tested it.

As far as the cooling system problems, you may want to flush and fill the cooling system, and make sure you pull the radiator out and flush it completely. Crap, gunk and rusty scale could be blocking some of the tubes in the radiator, cutting it's efficiency. Replace the cap and thermostat. Fill with 50/50 coolant. Toyota red is best. Anything good for aluminum protection is OK. I use distilled water. Tap water can contain chemicals that may shorten the life of the anti-rust and water pump lubricating additives in the coolant.

Of course, this is if you rule out a need to re-build. That should be the first focus. If the turbo is leaking oil, it will get sucked through the intercooler on it's way to the engine. You should see oil in the piping. If that is OK, a leak-down test will reveal the condition of the valves and rings. Any shop should be able to do this. If it is out of spec, a rebuild will be required.

mine drops to about 5 at idle, and picks up to around 20-35 ish while driving around.

so now its not the rings, its the bearings. wooo

yes, use distilled water for those reasons. only use regular water if you DESPERATELY need to, and afterwards do a flush of your system. itll bite you in the ass in the long run.

Busted Knuckles · 07-08-2008, 09:45 AM

Sidewinder, you can survive for a bit if you switch to 20W/50 oil, and use a bottle of STP with every change. This bumped my idle pressure to 10-15 psi, and has been holding there for a year. I'm planning on an engine rebuild. It will probably happen this winter or next spring.

SideWinderGX · 07-08-2008, 01:52 PM

I've been driving this way since i owned the car, which was a little over a year ago. No problems yet, so i dont wanna throw to 20w50 in there too soon lol

It might even be something else, hopefully.

Regardless, its getting a rebuild down the road.

mkiiisupra · 07-08-2008, 11:57 PM

Quote:

Originally Posted by Busted Knuckles

Sidewinder, you can survive for a bit if you switch to 20W/50 oil, and use a bottle of STP with every change. This bumped my idle pressure to 10-15 psi, and has been holding there for a year. I'm planning on an engine rebuild. It will probably happen this winter or next spring.

Please dont do this.... Putting thicker oil in your car is not the answer....

please read the oil link in my signature Busted Knuckles before you advise someone else....

mkiiisupra · 07-09-2008, 01:54 AM

The Following is from jdub over at supramania. Knows alot about oils

A 20W-50 will increase oil pressure and keep the bearings from touching the crank journal/rod end - False
A thicker oil will increase oil pressure in the 7M, but only to a point. The design of the 7M has the oil relief valve set at 63-71 psi...over this oil is simply routed back to the pan. More importantly, the oil cooler valve on the stock filter head operates at 40 psi and you have a controlled "leak" from the oil squirters on a turbo motor. Pressure is resistance to flow...a 20W-50's increase in pressure means that it does not flow as well through the bearings or to the top of the motor. Considering a 20W-50 oil is 3-4 times thicker cold than a 5W-30, it's significant. This means a couple of things:
- On a cold start, you will have restricted oil flow where you need it the most.
- The oil relief valve will cut the flow further by opening at the higher pressure and dumping oil back into the pan.
- It will take longer for the oil to get to the cam shafts...the small diameter hole in the middle does not facilitate flowing high viscosity oil. Since the oil flows from front to rear on the cam shafts, it is going to take the #6 cylinder valves the longest to get the oil flow needed.
- The oil squirters spray pattern on the cylinder walls will degrade with a high viscosity oil...especially cold. It's simple...higher viscosity, lower velocity.
Oil pressure has little to do with the way an open bearing (like rod & main bearings) works. Like I said, these bearings depend on hydrodynamic lubrication to function...saying increased pressure will improve this is a very basic misunderstanding of how the bearings really work. The ONLY time I could see using a 20W-50 from a bearing standpoint is if you've built the motor for it by opening up the bearing clearances to get the flow...you will see some very experienced engine builders do this, mostly on race cars that get re-built every season anyway.

Busted Knuckles · 07-09-2008, 03:41 AM

mkiiisupra, I beg to differ on a few points.

Point 1: 20W50 is a recommended oil for the 7M-GE and 7M-GTE for ambient temperatures above 40 deg F, according to the owner's manual. So, the oil journals, including the cam journals, are sufficient for this viscosity. I live in Atlanta, and we only see temps below 40 for a couple of weeks in the dead of winter.

Point 2: Oil is pushed through the engine by pressure. The higher the pressure, the more oil is being delivered to all parts of the engine, especially to the top of the cylinder head. At idle pressures of 5 psi, less oil makes it to the cams, and more is running through the main bearings due to widened clearances due to wear. A heavier oil will push less through the mains, and force more towards the cams, as monitored by increased oil pressure.

Point 3: Since 20W50 is a recommended oil, you do not have problems within the oil delivery journals of 'choke points' where the oil delivery hole prevents the oil pressure from being delivered. Thus, the oil pressure is the same at the cam bearings as it is at the main bearings.

Point 4: Bearings get most of their protection from film thickness. Higher viscosity oils provide higher film thicknesses than lighter oils. Pure and simple. And as the bearings wear, and clearances widen, that film thickness may prevent a bearing from getting smoked.

I've read link after link from sites like Bob Is The Oil Guy and discussions that link to studies, like Technical Journal: R&D Review of Toyota CRDL

that specifically links light viscosity oils to increased wear in piston rings over higher weight oil specifically because of the lighter oil running off the cylinder walls faster. They also show increased wear in connecting rod bearings, cam bearings, and main journals.

07-08-2008, 01:52 PM	#5
SideWinderGX 3" Exhaust Join Date: Feb 2007 Location: Syracuse, NY Posts: 203	I've been driving this way since i owned the car, which was a little over a year ago. No problems yet, so i dont wanna throw to 20w50 in there too soon lol It might even be something else, hopefully. Regardless, its getting a rebuild down the road. __________________ my car: 1987 brownish Toyota Supra Turbo, automatic 7MGTE engine with ~100k miles on it.

07-09-2008, 01:54 AM	#7
mkiiisupra Lexus & 550's Join Date: Sep 2007 Location: Las Vegas, NV Posts: 570 Blog Entries: 1	The Following is from jdub over at supramania. Knows alot about oils A 20W-50 will increase oil pressure and keep the bearings from touching the crank journal/rod end - False A thicker oil will increase oil pressure in the 7M, but only to a point. The design of the 7M has the oil relief valve set at 63-71 psi...over this oil is simply routed back to the pan. More importantly, the oil cooler valve on the stock filter head operates at 40 psi and you have a controlled "leak" from the oil squirters on a turbo motor. Pressure is resistance to flow...a 20W-50's increase in pressure means that it does not flow as well through the bearings or to the top of the motor. Considering a 20W-50 oil is 3-4 times thicker cold than a 5W-30, it's significant. This means a couple of things: - On a cold start, you will have restricted oil flow where you need it the most. - The oil relief valve will cut the flow further by opening at the higher pressure and dumping oil back into the pan. - It will take longer for the oil to get to the cam shafts...the small diameter hole in the middle does not facilitate flowing high viscosity oil. Since the oil flows from front to rear on the cam shafts, it is going to take the #6 cylinder valves the longest to get the oil flow needed. - The oil squirters spray pattern on the cylinder walls will degrade with a high viscosity oil...especially cold. It's simple...higher viscosity, lower velocity. Oil pressure has little to do with the way an open bearing (like rod & main bearings) works. Like I said, these bearings depend on hydrodynamic lubrication to function...saying increased pressure will improve this is a very basic misunderstanding of how the bearings really work. The ONLY time I could see using a 20W-50 from a bearing standpoint is if you've built the motor for it by opening up the bearing clearances to get the flow...you will see some very experienced engine builders do this, mostly on race cars that get re-built every season anyway. __________________ 1990 Toyota Supra Turbo A/T ------------------------------------------------ Questions about oil? take a look http://www.supramania.com/aehaas/

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
ABS Problem?	rasclaat_98	MKIII Supra	6	12-13-2010 09:53 PM
speed sensor problem	nadircicek	Non-Generation Specific Questions	8	10-09-2009 05:58 PM
found the problem	brs86supra	MKIII Supra	0	05-02-2006 03:42 PM
Boost Problem, I Guess	nonstop213	MKIII Supra	0	02-23-2006 07:32 PM
tsp problem for na t supra	jdlee123	MKIV Supra	0	09-02-2005 06:01 PM

07-06-2008, 12:59 PM	#2
Busted Knuckles 12psi boost Join Date: Dec 2007 Location: Atlanta Posts: 300	I agree with the previous post that questioned the amount of blow-by to oil pressure fluctuations. My oil pressure drops at idle, and picks-up at driving, but this has to do with worn bearings, not excessive blow-by. I don't have excessive blow-by. And yes, I tested it. As far as the cooling system problems, you may want to flush and fill the cooling system, and make sure you pull the radiator out and flush it completely. Crap, gunk and rusty scale could be blocking some of the tubes in the radiator, cutting it's efficiency. Replace the cap and thermostat. Fill with 50/50 coolant. Toyota red is best. Anything good for aluminum protection is OK. I use distilled water. Tap water can contain chemicals that may shorten the life of the anti-rust and water pump lubricating additives in the coolant. Of course, this is if you rule out a need to re-build. That should be the first focus. If the turbo is leaking oil, it will get sucked through the intercooler on it's way to the engine. You should see oil in the piping. If that is OK, a leak-down test will reveal the condition of the valves and rings. Any shop should be able to do this. If it is out of spec, a rebuild will be required.

07-08-2008, 09:45 AM	#4
Busted Knuckles 12psi boost Join Date: Dec 2007 Location: Atlanta Posts: 300	Sidewinder, you can survive for a bit if you switch to 20W/50 oil, and use a bottle of STP with every change. This bumped my idle pressure to 10-15 psi, and has been holding there for a year. I'm planning on an engine rebuild. It will probably happen this winter or next spring.

07-09-2008, 03:41 AM	#8
Busted Knuckles 12psi boost Join Date: Dec 2007 Location: Atlanta Posts: 300	mkiiisupra, I beg to differ on a few points. Point 1: 20W50 is a recommended oil for the 7M-GE and 7M-GTE for ambient temperatures above 40 deg F, according to the owner's manual. So, the oil journals, including the cam journals, are sufficient for this viscosity. I live in Atlanta, and we only see temps below 40 for a couple of weeks in the dead of winter. Point 2: Oil is pushed through the engine by pressure. The higher the pressure, the more oil is being delivered to all parts of the engine, especially to the top of the cylinder head. At idle pressures of 5 psi, less oil makes it to the cams, and more is running through the main bearings due to widened clearances due to wear. A heavier oil will push less through the mains, and force more towards the cams, as monitored by increased oil pressure. Point 3: Since 20W50 is a recommended oil, you do not have problems within the oil delivery journals of 'choke points' where the oil delivery hole prevents the oil pressure from being delivered. Thus, the oil pressure is the same at the cam bearings as it is at the main bearings. Point 4: Bearings get most of their protection from film thickness. Higher viscosity oils provide higher film thicknesses than lighter oils. Pure and simple. And as the bearings wear, and clearances widen, that film thickness may prevent a bearing from getting smoked. I've read link after link from sites like Bob Is The Oil Guy and discussions that link to studies, like Technical Journal: R&D Review of Toyota CRDL that specifically links light viscosity oils to increased wear in piston rings over higher weight oil specifically because of the lighter oil running off the cylinder walls faster. They also show increased wear in connecting rod bearings, cam bearings, and main journals.