Newly rebuilt 3.2 SS not warming up?

[ohecht]

I just finished the rebuild of my 3.0 into a 3.2 SS. Here are most of the specs just in case anything here could account for my issue: 10.5 CR JE pistons, Mahle cylinders, Xtreme dual plug heads with RSR valves and significant port work, extrude-honed 3.2 intake with enlarged throttle body, Supertec-massaged stock oil pump, Injector Dynamics, ID725 injectors, Megasquirt 3 with dual EDIS ignition, 993 SS cams, B&B 1 5/8" exhaust.

As I'm starting to tune the engine, the problem I'm having is that it doesn't seem to be reaching operating temperature at all. I have two separate gauges and temperature senders...the stock one (replaced during the rebuilt) feeding the gauge in the dash (upgraded with temperature markings but that was done ~20 years ago) and a Clewett sensor in the left cam cover sending temperature readings to the MS ECU. I also have a stock 3.2 CHT sensor that I haven't yet hooked up but I might now just to figure out what's really going on. The old engine used to always reach ~180F within a few minutes of driving, but this one will barely move at all and then never get above the 120 mark even as I've been driving pretty hard to seat the rings...lots of 3rd gear pulls from 2k to 5k+ RPMs and then coasting back down for about 20-30 minutes at a time. The car is running very rich because the ECU thinks it's still warming up. The ECU is seeing even lower temperatures from the Clewett gauge.

If only one gauge was showing low, I'd suspect a problem with it, but the fact that both are showing low temps as independent gauges has me stumped. I also replaced my oil lines with ER finned ones but I would not expect those to have this much of a cooling impact. I've had a front-mounted oil cooler since I got the car in 2000 so it's always been fairly easy to keep consistent temps whenever moving.

Is it possible to install the engine t-stat in a way that would make it always flow oil to the front cooler? If so, I would still expect the car to eventually reach something close to it's old operating temp...wouldn't it just take longer? I don't think I got any of the connections wrong in the t-stat in the wheel well, but could something there be causing an issue like this? I have verified that warm oil is flowing to the front of the car, but I have not yet checked to see if it's not flowing there when the car is just started, etc. The only other change that could possibly impact this is that the bottom engine oil line from ER is the one that runs over the transmission, so it's definitely further from the exhaust heat, but I still don't think that would make the car run this cool...

Thanks in advance...I need to get into the normal operating temp range to do any real tuning!

Olivier

[boyt911sc]

Originally Posted by ohecht

I just finished the rebuild of my 3.0 into a 3.2 SS. Here are most of the specs just in case anything here could account for my issue: 10.5 CR JE pistons, Mahle cylinders, Xtreme dual plug heads with RSR valves and significant port work, extrude-honed 3.2 intake with enlarged throttle body, Supertec-massaged stock oil pump, Injector Dynamics, ID725 injectors, Megasquirt 3 with dual EDIS ignition, 993 SS cams, B&B 1 5/8" exhaust.

As I'm starting to tune the engine, the problem I'm having is that it doesn't seem to be reaching operating temperature at all. I have two separate gauges and temperature senders...the stock one (replaced during the rebuilt) feeding the gauge in the dash (upgraded with temperature markings but that was done ~20 years ago) and a Clewett sensor in the left cam cover sending temperature readings to the MS ECU. I also have a stock 3.2 CHT sensor that I haven't yet hooked up but I might now just to figure out what's really going on. The old engine used to always reach ~180F within a few minutes of driving, but this one will barely move at all and then never get above the 120 mark even as I've been driving pretty hard to seat the rings...lots of 3rd gear pulls from 2k to 5k+ RPMs and then coasting back down for about 20-30 minutes at a time. The car is running very rich because the ECU thinks it's still warming up. The ECU is seeing even lower temperatures from the Clewett gauge.

If only one gauge was showing low, I'd suspect a problem with it, but the fact that both are showing low temps as independent gauges has me stumped. I also replaced my oil lines with ER finned ones but I would not expect those to have this much of a cooling impact. I've had a front-mounted oil cooler since I got the car in 2000 so it's always been fairly easy to keep consistent temps whenever moving.

Is it possible to install the engine t-stat in a way that would make it always flow oil to the front cooler? If so, I would still expect the car to eventually reach something close to it's old operating temp...wouldn't it just take longer? I don't think I got any of the connections wrong in the t-stat in the wheel well, but could something there be causing an issue like this? I have verified that warm oil is flowing to the front of the car, but I have not yet checked to see if it's not flowing there when the car is just started, etc. The only other change that could possibly impact this is that the bottom engine oil line from ER is the one that runs over the transmission, so it's definitely further from the exhaust heat, but I still don't think that would make the car run this cool...

Thanks in advance...I need to get into the normal operating temp range to do any real tuning!

Olivier

Oliver,

Start by testing the engine and auxiliary thermostats for its operation. Both thermostats should be closed below 180 F and would gradually open by 185 F (+/-) and fully open at 195 F (+/-). A fully stuck open thermostat would take a very long time to get to operating temperature and may not even get to operating temp. if the weather is too cold like in the winter time. Until you do a physical test and examination of these thermostats, you will be just quessing.

Tony

[ohecht]

Thanks, Tony...what's the best way to test the two thermostats? Do you mean physically removing them and testing them in a water bath? I think I could do that with the engine one, but I'm not sure about how to do that with the one in the wheel well.

[cmonref]

Oliver,

Here is a DOCx of a KTL thread on the external thermostat. It shows which is the thermostat and which is the pressure bypass. Remove the cap from the thermostat and remove the internals. The internals include the thermostat that you would check in the water bath.

If your external thermostat has not been out for a while, you may have to remove it. That is the subject of several good threads. You may not be able to get the thermostat cap off while the body is in the car since it is not mounted to anything -- it is just held in place by the oil lines.

Good luck!

PS: docx a couple of posts below ...

[boyt911sc]

Originally Posted by cmonref

Oliver,

Here is a DOCx of a KTL thread on the external thermostat. It shows which is the thermostat and which is the pressure bypass. Remove the cap from the thermostat and remove the internals. The internals include the thermostat that you would check in the water bath.

If your external thermostat has not been out for a while, you may have to remove it. That is the subject of several good threads. You may not be able to get the thermostat cap off while the body is in the car since it is not mounted to anything -- it is just held in place by the oil lines.

Good luck!

Oliver,

I am away from home and have no access to my documents. I had posted several pictures of the water bath for testing the thermostats. The engine and auxiliary cooler thermostat are basically the same unit. On the average, I found out that these thermostats would start to open @ 185 F. and fully opened @ 195 F. Ideally an oil bath is used for such a test but a water bath will work. Use a flashlight to inspect the valve movement during the test. The key is setting up a couple of temp. probes to determine the temp. of the bath

The auxiliary cooler thermostat are iinside the auxiliary thermostat and by removing the retaining cap which is sometime stubborn would allow you to get the thermostat out. This particular test is broadly discussed in the Technical Forum. I had a few posts and pictures regarding this subject in this forum.

Tony

[cmonref]

I wish I had a nickel for every time I have forgotten to attach a file ... And then I have to copy it in because a docx can't be imported.

External Oil Thermostat Operation
By KTL

See below the labeled picture.
Port 1 is the incoming oil to the t-stat
Port 2 is the oil returned to the oil tank
Port 3 is the oil going forward to the oil cooler
Port 4 is the oil returning to the t-stat from the oil cooler.



Here's how it works, which most people don't fully realize. When cold (below 180F) the oil comes into Port 1 and is passed through both Port 2 to return the oil back to the tank, AND partly through Port 3. Port 3 is actually open to send oil forward to the oil cooler at all times regardless of temperature. However, Port 4 is closed and therefore does not allow oil to actually flow through the cooler. The oil just "stacks up" and thus all the flow goes through Port 2.

Only when the regulator opens at 180F (or is stuck open, which occurs much more often than people realize) to allow Port 4 to pass oil, will there be flow through the cooler. When Port 4 is opened by the movement of the t-stat regulator the oil no longer passes directly from Port 1 to Port 2. The internal connection between Port 1 & Port 2 is closed (by the reduction in “overpressure” since the Port 3-Port 4 is open and provides a flow path with less pressure loss) and the oil is forced to flow as follows: Port 1 -> Port 3 -> Cooler -> Port 4 -> Port 2.

[ohecht]

Thanks again Tony and cmonref...I will try to remove and test the t-stats today. I will also connect my CHT sensor and get a third reading that's not based on oil temp.

I have a couple more quick questions and some more info in case it helps diagnose what's going on:

1) Is it even possible to install the engine thermostat backwards so that it would prevent the engine from fully warming up? It's been a while since I installed it during the rebuild, but I think I remember it being obvious how the ports on the thermostat itself lined up with the openings in the engine case. If it was easy to install backwards, I'd think there'd be a lot of specific instructions and cautionary tales about it if not some type of mistake-proofing in the physical design of the parts.

2) cmonref, that picture is very helpful and I will verify all of my connections. To remove the thermostat itself, do I need to access the section you have labeled as "Temperature Regulator Section"? I assume a giant slotted screwdriver would be useless in there...is a pipe wrench or something similar the best way to go? The more I think about this, the more I think my problem is that the external oil thermostat is stuck open.

Additional info from testing yesterday:

The oil lines to the front cooler do seem to be cold even about 10 minutes after starting the car, but are definitely hot after any type of drive, so it does seem that the oil flow is being managed at least somewhat correctly...I will check it anyway.

I was doing some extensive idle tuning yesterday and the dash gauge did eventually reach its old "normal" indication of ~180F, so it does warm up eventually. This took a very long time, though. I immediately went out for a quick drive to get some tuning done at temp under load, and noticed that the temperature was back down near 130F within just a few minutes of driving about 45 mph and not driving gently, either. The car would never cool down that quickly before, but it does seem to indicate that air flow is a major factor. Could the finned oil lines and fresh "everything else" in the engine really make it cool down so effectively through the front cooler?

Finally, I did my second oil change last night...the first was after the first 20 minutes at 2k rpm. Both times, I drained the oil when it was very hot (within about 5 minutes of shutting the car off) and noticed that the oil was extremely thin...almost like water. The first time, I thought it was just due to the assembly lube and other things being flushed out, but the same thing happened the second time. It could be just that I'm changing it when it's much warmer than I would normally...I'd usually wait at least 20 minutes before draining the oil, but I mention it here just in case some type of breakdown in the oil is causing the oil cooling system to not act normally. The oil is non-synthetic (and cheap) 20w-50 that I've been using for the frequent changes during break-in.

Thanks again,

Olivier

[cmonref]

Oliver,

#1: I can't imagine installing it backwards -- but I've never tried. The threads on all four ports are identical, so it MAY be possible, but I doubt it.

#2: You can remove it on the car IF the threads let you. It is mounted on the hard lines going forward, so there is not very much "grip" to hold against a wrench. Give it a try if it has been installed in the past couple of years with lots of antiseize on the threads. If anything sticks, go to plan B which is to remove the whole mess from the front cooler to the engine connections (that drops all four oil lines still attached, letting you put it on the bench to get a good grip on it.)

#2 supplement: I assume there is room to put a socket-screwdriver in to remove the cap and retrieve the thermostat (my car is at the shop for paint so I can't look.) If the cap can be removed, so much the better and you are all set. On mine, in prep for paint, I had to dremel a notch in the cap, on the bench, to get a cold chisel on the cap to break it loose. Our host has new ones with the aluminum crush ring. I could not break it loose with a pipe wrench with the thermostat in a vise.

If you buy a new socket-screwdriver (don't remember the actual name!), get one that fits BOTH slots. One is smaller than the other. At NAPA, I said "the biggest you have" and it was too big for the thinner slot. (That said, I do not recall which is the thinner one -- but I chose to tighten it with a pipe wrench.

Remember that the thermostat is BEHIND the cooler in the oil flow path. Hot oil fills the line to the cooler but the thermostat prevents it from flowing THRU the cooler and back to the tank -- thus no cooling of the oil.

My thermostat is all cleaned up and in a plastic bag if you want to handle one before tackling this.

Brian

[ohecht]

Thanks again Brian. I got lucky removing the tstat...the trick was supporting the housing with a jack stand and it broke loose on my first real pull with a pipe wrench. As far as I know it hasn't been opened in 33 years and I know it hasn't in the past 15 years so I feel fortunate.

The tstat itself was very hard to extract...I needed to pull it out with a pick. It was all the way recessed in the housing, which I think is the closed position from my later tests...see below. This was after cooling down for 12 hours overnight.

Am I right in understanding that the entire tstat body slides within the housing as the small "piston" extends from the side of the tstat opposite the plug opening? See the pics below of what it looked like just after I removed it and during the hot and cold water tests. It did seem to open around 190f but it is taking quite a while to close in an ice bath.

Since I know hot oil was flowing through the lines last night and the tstat was in the closed position (if that's right) this morning, does that mean the tstat is working and also sliding within the tstat housing?

Oh, and my question about installing a tstat backwards was about the one in the engine...still not sure about that.

I can't seem to upload pictures from my phone so I'll try to describe them.

The tstat was all the way in the "back" if the external housing with the engine cold and nothing was protruding from either end.

In a hot water bath, a piston extended lost one end of the housing at around 185f.

The piston did not retract in its own in a cold water bath, but I imagine the spring between the tstat and the cover would push it back into the retracted position by pushing the entire tstat back against the back wall of the external housing.

Thanks again,

Olivier

[cmonref]

Oliver,

Looks like you got REAL lucky on getting the t-stat out. Whoever put it in most recently (15 years?) did it right. I'll bet you found the hose threads well coated with antisieze.

Sounds line your t-stat checks OK in the water bath. Your findings are consistent with Boy911SC's tutorial on the subject (in another thread.) Mine also returned quite slowly from open to closed in the ice water bath.

If the t-stat needed a pick to remove, it might have been stuck and not moving. I cleaned out the bore of the housing and the t-stat on mine with crocus cloth to smooth the interface and to prevent that from happening. Then I cleaned the housing and flushed it really well before reassembly.

Since I know hot oil was flowing through the lines last night and the tstat was in the closed position (if that's right) this morning, does that mean the tstat is working and also sliding within the tstat housing?

If oil is flowing, both hard lines will be REALLY hot. If the t-stat is stuck and oil is not flowing, the lines will be warm -- as opposed to REALLY hot -- and the line TO the cooler will be warmer than the line from the cooler. The static oil will be conducting heat which should produce that result.

We have not talked about the pressure bypass valve. If it is stuck in the open position, it would bypass the oil to the tank. I think this bypass would occur even if the thermostat were opened also -- altho' I imagine that SOME oil would flow thru the cooler under those conditions. To check that, remove the OTHER cap and pull out the pressure bypass assemblies. That would let you do the crocus cloth treatment to both bores to insure smooth operations in the future.

Brian

[ohecht]

Thanks again Brian and all.

I tried to get the pressure relief valve out but there's no way I can get a good grip with any type of wrench while it's mounted in the car and I didn't want to press my luck with things today. I did remove the two oil lines to the engine and tank to see what I could see, but I can't see into the two openings connecting those passages. The bottom one felt open when I put my finger in it, in case that says anything about what position the valve was in when the car was stone cold.

I also checked the engine thermostat and it seems to be working fine...see pics below. It opened right around 190f and more importantly closed very quickly when I put it in room temperature water. I assume its supposed to work so that one or the other opening on the tstat is open...they were never open at the same time. I also verified that the openings on this thermostat were aligned with the ports in the engine case...you could install this backwards but I think you would have the opposite problem that I have as the ports would be blocked at all times, and it is pretty obvious how it needs to be installed to function.

I haven't tried to warm up the car again to see if any of this tinkering loosened anything up...I'm waiting for the Curil-T on the engine tstat o-ring to cure some more and I should be able to see how things work tomorrow morning. I will time how long it takes to get to 180f and keep my hands on the front oil lines to see when they get warm and then hot.

One thing I keep coming back to now since the tstats seem to check out is that, once I did reach 180f yesterday, it cooled down to 120f in about 5 minutes of driving. The car never used to do that...180f was pretty much the minimum temp once it was reached, even with highway cruising on cool days, etc. The only things that I think could explain that are either a) the oil cooling system has somehow gotten significantly more efficient, or b) the engine is somehow running much cooler after the rebuild.

The finned oil lines (and replacing all the 33-year-old oil lines) were the only cooling system upgrade, and I really don't think that could have this effect.

Is there anything in the specs of my rebuild that could explain running this much cooler?

I've been running very rich as I continue to tune the car...mostly because the car thinks it's still warming up (or it actually is)...could running rich (maybe 11-12 AFR at times) cool things down that much?

And the worst possibility...could I have done something wrong in the rebuild to cause this? Could an internal oil passage be blocked that's either preventing the proper circulation of oil period or just preventing it from reaching the really hot parts that need to have heat carried away from them by the oil? What if the cams aren't getting oil or some of the piston squirters are blocked? I tested them all and replaced most if not all of them, but they were a major PITA to get spraying...even the new ones. Could there be air trapped in the oil circuit somewhere?

I'm starting to get paranoid...

Thanks again,

Olivier


tstat closed...as removed from a stone cold engine:



tstat open...after 200f water bath:

[ohecht]

Brian,

I just realized that you're in Richmond too...maybe you can see the car in person sometime. I usually go to the bi-weekly Saturday Cars and Coffee events although I haven't had the car there during the rebuild...maybe I will be able to bring it next Saturday.

Olivier

[cmonref]

Oliver,

Yup, Chester, just south of the courthouse on Rte 10. Cars N Coffee is 10/3 due to rain on yesterday's scheduled date of 9/26? If yes, I'll drop in. 911 is in for paint, so it will be a seal gray Cayenne. Hope to see you there.

Brian

[ohecht]

Yes...the next one should be on the 3rd...hope to see you there. I should be in the only 911 with a bike rack on the roof if I make it in that car...

[Sub8]

You say you are running rich, by how much? Rich everywhere with regards speed and load?

If so that will drop combustion temps which will affect warmup rate.

You could try recalibrating to your current running temp and see if that helps. Rich afr will not help ring seating.

[ohecht]

Not very rich...maybe 11 or 12 AFRs when I was first starting the tune, but now I'm staying between 12.8 and 15-16 on deceleration (I haven't tuned acceleration or deceleration yet), so I doubt I'm running rich enough to make this much of a difference.

I think I know what happened with the factory gauge, and I guess I coincidentally also have an issue with my additional temp gauge for the MS EFI. I've always had the numbered gauge in this car...the PO must have upgraded it. I replaced the sender during the rebuild and I must have ordered the standard gauge for an '82. I'm waiting for the car to cool down to compare the part numbers and probably swap the old one back in. That would explain the dash gauge acting normally but reading about 60f low at all points. I still need to address the other sender...I got the resistance readings from a few temps in a water bath and still can't get it to read even close to right...I'll get another sender asap and go from there.

I hope I'm right about the factory gauge and that would mean I probably didn't do something catastrophic during the rebuild to prevent the oil from reaching temperature, etc.

In case anyone's interested, here are the results of my warmup test today:

- After about 10 minutes of warming up, one of the lines leading to the front cooler got warm to the touch...the line from the most forward port on the t-stat housing...port 4 in the picture above, I think.

- After about 15 minutes warming up, that line got too hot to touch

- 5 minutes after that, the other line quickly went from still very cold to too hot to touch. Once the dash gauge indicated 120f, both lines were too hot to touch, and I think the dash gauge would have read 180f if it had the right sender.

- I can tell from the ambient heat around the engine, heat shimmer behind the car, general temps in the engine compartment, and ticking after it's shut off, that the car is actually reaching operating temperature...it must be the (two) temp senders, having both of them read low at once just threw me off the trail here...thanks again for all the help troubleshooting, though!

[ohecht]

I realized I never closed out this thread with the solution...dumb as it was. I had the air and oil temp sensors wires reversed in the Megasquirt harness! I must have connected ~100 wires installing the engine and rewiring the entire EFI harness along with most of the wires to the rear of the car, and reversing one yellow wire with one orange wire was the one thing I got wrong! I should have figured it out much more quickly, but the high air temps prevented it from being super-obvious...I ended up figuring it out when I disconnected a sensor while looking at the EFI gauges on my laptop and the wrong gauge went to zero...