2056 with D-jet. After reading some of the recent oil temperature threads I decided I should probably check how I'm running. Don't have gauge, but I had my dipstick thermometer that was still in my old 1.7L engine. After 20 minutes of spirited driving around the neighborhood in 88 degree weather I was a little distressed to see temps on that gauge running close to 240. Yikes! Maybe not an emergency, but not optimum either. So this weekend I:

-made sure I had right amount of oil (running Joe Gibbs 20W50 right now)
-made sure all the engine tin/warm air guides and heater components are in place (I had removed some of this a month ago when fixing the heat exchangers)
-checked and reset timing (was probably advanced a little too much),
-temporarily disconnected the thermostat cable from the top so the flaps are, in theory, always in max cooling position.

None of this seemed to help. Funny thing is my head temps are normally cool. Driving around town (lots of costing and downshifting at lights) keep me in the 270-280 range, and the only time I ever really north of 300 degrees is when I'm going up a hill or if I'm running a few miles at 65 to 70 mph (and then it maybe gets to 335) out on the "freeway." Car is running great otherwise.

So I'm wondering if the flaps truly are working. When I had the engine out a few months I definitely made sure, but I don't know if something is sticking or what. Right now that's my only working theory on why my head temps are cool to normal and the oil temp is warm to hot.

Any thoughts? Any good way to verify flap operation without completely removing the tin (something I don't relish doing with the engine in the car).

Also, engine came with this oil temp sending unit installed (below). It's definitely the source of one of my minor oil leaks. Anybody recognize it? I'd like to go ahead and install a gauge that works with this sending unit, and also see what I need to do to stop the leak.

Click to view attachment

TIA, fellas.

Flaps are working or your heads would be roasting.

Zach

What have you got to measure head and oil temps? If they're truly that low then the high oil temps seem unlikely, the other way around seems more possible.

Thanks Zach, thanks Porschef. Zach, so you don't think my issue is necessarily flap not "closing" over the oil cooler to get max heat to it? I was kind of under the impression that the cooling system sort of traded head cooling for oil cooler cooling as it warmed up, but maybe that's a bad understanding of how it actually works.

Porschef, my head temp is a Dakota Digital setup under spark plug #3. The oil temp is that "mainely by design" dipstick setup. I tested it this weekend in boiling water, and it seemed close enough. I would like to get a gauge to go with that unknown sending unit in the picture above. Are those pretty universal, or do I need to get a sending unit specific to the gauge?

Thanks again.

Sender is specific to the gauge ... never seen that setup.

Cooling flaps ... passenger side is open to the cylinders, but not the oil cooler when cold. When hot, the flap closes down over the oil cooler to direct air into it. Drivers side is closed off when cold and opens when hot for air to the cylinders.

Failsafe is the position when the engine is warm (assuming the spring is working).

Have you cleaned your oil cooler? I put them on a lift and shoot a can of brake cleaner from the underside and then blow the fins out with an air nozzle. I realize that any gunk gets pushed over the cylinders, but unless I drop the engine I am not taking the tin off to get to it.

Hey Ron - I replaced the oil cooler seals when I had it out, but I don't recall the cooler being abnormally dirty (but then I probably didn't know what I was looking at). Based on what you're saying I may be able to clean it with the engine in the car, right?

If the sending unit is not recognized, is the fitting fairly standard (e.g., 1/8th npt)?

Thanks.

The taco plate for the sender is odd, factory taco plate the sender is on a 45 degree angle.

I'd say it's custom taco so the sender thread could be oddball.

run 10-40 or 10-30 and let the oil run through the motor a little faster

Hi Beatnavy,thats getting warm....or is it,check to make sure the gauge is rated to the sendor,example 150C max gauge must use 150C sender,then get your cooling flaps/thermostat sorted ASAP,cheers.

good reading here http://www.smartsynthetics.com/motor-oil-viscosity.htm

Hmmm....ok, not necessarily what I was hoping to hear, but makes sense. Thanks Mark.


Yes, I'm planning on trying Brad Penn 10W40 to see if that helps. But I was hoping to throw an oil temp gauge into the cart as well. May have to wait tho...

Looks like your taco plate is one of Jonesy's billet taco plates.....it's got the same 14mm x 1.5 thread as the stock sender.

His billet taco plate looks like the one that Jonesy out of the UK was selling. I have one in my basement. The threads are the same but they are perpendicular instead of being at an angle. Beat Navy are you using the factory OE sender or the shorter one?

David

Hi David - I don't know what sender I'm using. It came with the engine. That's two votes for "Jonesy's taco plate." Any thoughts on what gauges (other than OEM) will work with that? It was reading about 2K of resistance ambient and then around 12 ohms when it was hot (roughly 240 degrees). Or am I better off just getting another gauge/sending unit that fits that "taco" plate?

Thanks for everyone's help.


Welcome to the World, porschetub! Glad to see you made the trip over from the Bird!

The Jonesy "taco plate" makes additional sense. After searching I found he also makes a "mini deep oil sump" or tuna can that I think I also have:

Click to view attachment

if any of you are selling one of those billet taco plates on the cheap, I am keep to take it from you

Yea thanks,thought it was time for the move,enjoying it so far,lots on here know way more about my car that i do .
I have always liked VDO stuff,buy a matched gauge and sender to suit the temp range you need and go from there,you need to sort this to set a baseline for further work into your problem.
Coolers......I swapped my 911 cooler for one modded for a 914/6,it had been cleaned by PO the cheap and nasty way,I had it ultrasonically cleaned and they said it was filthy,really worth doing if you can't fully sort your problem by other means,cheers.

Cheap easy check. Buy a USB camera from Amazon and inspect the flaps. Pretty easy to see if you go in through timing port.

the temps you are seeing are similar to the temps i have been seeing as well, but also found out that checking and calibrating my dipstick thermometer that my gauge was reading 30-40 degrees warmer than dipstick.
- i have the same billet deep tuna can and also the billet tuna can replacement as does Jim Hoyland. I have ordered a new VDO gauge that iwll match the sender properly and should give a more accurate indication of oil temp. my current gauge is off brand from before and not correct.
- i just switched to a 10-40 oil from 20/50 and while i only have one day of driving this past weekend after the oil change it appears this made a measurable difference in my temps, i did not measure an oil temp over 205-210 this weekend and i had been pushing that 240 range before. the real test will be when i take it out on a hot day for more spirited driving. i was and still may consider replacing the stock cooler with the set up that Chris Foley has, or just an add-on aux. cooler that several other members have put in that seems to have worked well for them. - i still am going to go back to recheck my timing as that will matter for overal engine temp but if you have good head temps i would say that is not your problem. - a good racing oil will not break down at 250 or even 275, but som oils will begin to do that at that point. last year at octeenerfest i talked to John Forbes about this, because when pushing hard going up the mountain with our group i hit that 250 point and was very concerned.
see how much change it makes with the other oil as i am before spending a bunch of extra cash on something else.

Hey Mike - that's a good idea. Just bought one. Could come in handy for many reasons.


Hey Phil - I am planning on switching to 10w40 to see if that helps. I'd really spend my time/money on something other than installing an oil cooler on a -4. Of course I don't want to spend my money on rebuilding a fairly fresh engine either. I'm going to go shopping for a VDO gauge...

Thanks again for everyone's help.

Chris's oil bypass spring made a huge difference in my temps. Essentialy all oil goes through cooler.

I did the bypass valve first, helped a bit, next i did the deep tuna can, and now went back to the 10/40 oil and i have seen about a 15-20 degree decrease in our hot temps. If it really makes that much of a difference and i see that the temps stay around 220 - 230 max when hot and driving hard, or at highway speeds then i will not do the oil cooler. I want to prevent high cylinder head temps , so i might put in a cht sensor on #3 and see where that is as well - how did you install yours?

I know that others may not agree, but the oil weight makes a huge difference. when I changed to 20/50 I noticed the surge within 15 minutes of hard driving.

Now I run under 200 .

You noticed it dropped back down when you switched away from 20/50? To what?

Up or down? Sorry but your post does't make much sense.

I was initially using 10/40, I did an oil change using 20/50 and the temp surged 20 degrees F.
I went back to 10/40 and I am running back to normal 20 degrees less.

Ambient temps and gearing heavily impact oil temperature. Tuning has impacts as well, mostly in regard to timing being too far retarded.

I run my 2.0 D-jet with a stock cooling system pretty hard in the summer months with a mix of cruising & stop and go traffic. I run Quaker State Defy 10w30 semi-synthetic oil. I don't ever recall oil temps going above 220 on the VDO oil temp gauge.

Do you have the plastic air flaps attached to the rear of the floor pan? I've been told they create a negative pressure in the engine bay and assist with cooling at speed.

I run Brad Penn 15/40w and added a Scat 1.5 qt. sump. Runs cool as a cucumber. If you did not look at your oil cooler real close when you rebuilt your engine the fins are full of oil and dirt.

I don't think the oil cooler was in bad shape. Here's a pic when I replaced the seals before installing the car. The engine was fairly clean when I got it and I cleaned it up some more and powdercoated the tin, so I got a chance to look over it pretty good.

Click to view attachment

Bob, I do NOT have those undercarriage flaps or air baffles (or whatever they are) on my '72. I have seen people mention those before, but not sure how effective or important they are.

I have some Brad Penn 10W40 on order. Gonna try running that while it's still hot outside to see if it makes a difference. Also have a VDO on order to help me monitor it while I'm driving.

I agree and this can be what is causing hot oil and cold head condition, verify your timing.

Hi Mark - I did. It should be right on now. I said it was slightly advanced before when I meant to say slightly retarded. That may have contributed some.

interesting, as i have to verify this but my idle si really too low since being in the shop the last time and i think the timing is a bit too retarded as well, so i'm going to go back and verify this tonight.
BTW those flaps matter. get them and install them. I think on these cars, especially the 2.0 every little bit matters. BTW i think on the oil issue the factory recommended 30 wt oil.
Phil

which VDO gauge did you get?( been looking but did not purchase yet)

http://www.corvetteforum.com/forums/c3-tec...-test-data.html

FYI - found this interesting

I ran across this while trying to get more imformation on oil wear, zppd, etc etc.

its a list of highest rated oils for wear protection and breakdown, and how the test on "load carrying capacity and film strenght"
one thing to remember is dino oils will smoke and break down at a lower temp.
Zinc, ZPPD may extend the protective life of the oil but does not necessarily increase the protection, there is a difference.

i know a lot of ink has been spilled on this subject, and i know Jake may chime in because he has more experience in real world engine testing and development of both engines and oil, so he may shed more light on the subject and how these numbers can be interpeted.

Just a small follow-up on this thread. Last weekend I changed the oil and replaced the 20/50 with 10/40. Only got a little time to run it while hot outside, but it seems like it's running 10 degree cooler or more. I also purchased an oil temp gauge that matches my sending unit (AutoMeter) and tested it out before a full install. Interestingly enough that looks like it might be showing a significantly lower temp than the oil dipstick temp gauge.

Finally, got a pair of undercarriage cooling flaps in the mail, donated from a very active member here from PA (who has a thing for red 914's ). Gotta love the World! I'll try putting those on this weekend.

Clean the cooling fan....

Also ensure that timing is correct. I see lots of engines with retarded timing that run high OT and cool CHT,