SLOOOOOW warmup in cold weather
 

So it was around -19C this morning (0F), and it took forever for the engine to reach operating temperature! The first 20 minutes of driving were at between 30 and 50 mph, and the 8 still wasn't at operating temp after 20 minutes (as indicated on the coolant temp gauge). Only after I got to the stop'n'go bumper to bumper section of my commute did the engine finally warm up and the heater really start putting out heat.

I was a bit concerned that this might be the case after last week when the weather here started to get cold, but now I strongly suspect that the oil coolers are just too efficient - they shed heat faster than the engine can build heat in below freezing weather at speeds of 30 mph and up! I'm going to look into changing the oil cooler plastic mesh protection (see 'protecting your oil coolers' thread) for some solid plastic pieces to completely block airflow through the oil coolers.

Has anyone else experienced this yet? Thoughts on blocking the oil coolers?

Regards,
Gordon

maybe try blocking 1/4 to 1/2 to start?

I would think that most of the engine cooling is due to the coolant/radiator, not the oil cooler.

It could be as simple as them having to low-rated a thermostat, you could go for a warmer one. That or try blocking part of the radiator, at least then you have your temp gauge to let you know if you went too far.

Tape some cardboard over the radiator, or just use duct tape itself. I used to have to do the very same thing on my TZ250 racebike when the temps would drop, or else the poor thing would never warm up.
Using straigt duct tape makes it easier to find out just how much coverage you need.. although not having a "real" temp gauge could pose a bit of a problem :)

I have seen several aftermarket oil coolers that come with the cover you are trying to create. Don't some of the aftermarket coolers for the Miata have this feature?

You could also take some advise from the truckers. They will cover a portion of their front grill to help their engines maintain proper operating temperature. Maybe someone could invent a RX-8 bra that had optional grill flaps. ;)

I thought the radiator only comes into play when the coolant reaches op temp. I've thought(read somewhere), on startup coolant gets circulated only through the engine, then when it reaches op temp the thermostat opens and circulates it through the radiator to maintain the temp.
Please correct me if and where I'm wrong.

That's how it's supposed to work. If the engine is having trouble getting to temp in cold weather my first suspect would be the coolant thermostat is stuck open. I'm not familiar with oil coolers so don't know if there's a thermostat in that plumbing.

I'd be surprised if this was a design issue - environmental testing is done to ensure proper function at cold temperatures. Failure to reach normal operating temperature would not have gone unnoticed. I would not expect to have to take measures such as blocking ducts unless outside temperature is extreme (-20F or below).

It hasn't gotten that cold here yet, but even at around 30 Deg. F, my car takes a good 10 min. (part freeway) for the gauge to register full normal temp.

Gord, have you noticed condensation and foam on the dipstick as well? (most of my trips are 17 miles ea. way with 3/4's of it freeway)

You're right, that's how it's supposed to work. I think what's happening is that the coolant is trying to warm up, and the oil is also warming up, but the oil coolers are shedding so much heat with the greater temperature differentials across the oil coolers that they're losing more heat (when the car is moving at speed) than the engine can generate! The coolant possibly isn't getting enough heat to warm up even to the point of opening the thermostat.

Remember, the oil coolers (radiators) are there to cool the oil - I don't know if there is any thermostatic control of oil circulation through them, but there doesn't seem to be. If we block off the heat transfer from the oil coolers, then the coolant would be able to do it's job better. My Audi also has oil coolers, but IIRC there is some sort of thermostat-like temperature control on those. Not sure, though.

Here in Western Canada, it's pretty common to see bits of cardboard taped/tied in front of radiators and grilles of many of the vehicles! There's problems associated with that, though - I'd prefer to try blocking airflow to the oil coolers first.

Regards,
Gordon

This is totally unacceptable imo.. If your engine takes 10-30 min in order to get up to operating temps, that is really bad for engine wear isn't it? More growing pains..

So far the coldest morning here was only 28F, but I didn't notice the 8 taking more then about 2 miles to warm up... maybe you have a thermostat that has failed

Guys,
I read an interesting comment in a RX7 FAQ. ....Here it is.
The link for the entire FAQ is http://members.ij.net/mrmazda/cfaqmenu.html#FCF

--------------------------------------------------------------
"Why does my rotary Mazda have an oil cooler?

The rotors have no direct contact with the "cooling system", insulated well from the rotor and side housings, where the cooling passages connected to the radiator are situated. The eccentric shaft has oil jets that spray oil onto the back sides of the rotors to provide the required cooling. Without the oil cooler, the oil would get too hot and cease to lubricate.

On a related note, I've never seen dowel o-ring leaks on a 13B or pre-'83 12A. When rebuilding a 12A that has had dowel o-ring leakage, the old o-rings are very hard & will break if you try to bend them. This indicates that the '83-85 12A's get the oil hotter. In turn, this indicates that oil cooling in these cars is less effective. Part of this is the .6 quart lower overall oil capacity, but mainly it's the Rube Goldberg-style, two-step oil-to-water-to-air oil cooler not doing as well as the single-step oil-to-air type. This is something to remember if the opportunity to change to the pre-'83 or 13B type oil cooler presents itself. "
-----------------------------------------------------------

This makes me think that blocking the oil cooler might not be a good /safe idea. Seems to me you would be safer partially blocking the radiator if you want quicker warmup.

My office is only about 2 or 3 miles from my house and the car is at operating temp when I arrive at the office. It has been in the 20's each morning this week. Not sure why you have been having such a difficult time with warm-up.:confused:

Drove the car to work again today, but had to take a different route past our daycare to drop off my daughter. Temp only -8C (~17F), and the first 10 minutes of the drive was urban (ie 30 mph or less). The car was warmed up to operating temp within 10 minutes, as usual before yesterday (when it was significantly colder). The differences from yesterday? Less severe cold, and instead of heading out on the 40+mph thoroughfare with a cold(er) engine, the engine was warmed up before I got to the higher-speed section of this morning's commute. Oh, I also forgot to mention, my garage is well insulated, so the garage temp was about +5C (~42F) before starting out either day, the car itself wasn't all that cold...

I still think that in severe cold, the oil coolers will be doing too good a job. Maybe if the engine was at operating temp before getting to the faster speed route it might hold the temp OK. This will require more data from people in COLD temps (around -18C/0F) with varying commute patterns to see if it really is a problem!

Regards,
Gordon

damn Gord96BRG, i am in texas and thought the temp of 42F last night was titty cold, but my car has not had any problems warming up, so maybe the problem is something else if your garage is reaching on 42F. My old lexus themostat was so messed up the car would say it is overheating after starting the car, so maye it is the thermostat.

hey gord,here in ak we still havent had any snow but have had a few 25f mornings and i have noticed that my car since new has always seamed to take longer to warm up than any previous car i have owned.takes about 7 to 10 miles to warm the cab up.after 5 or so miles temp gauge is up and i have not noticied the excessive temp that people have complanied about in the cab.my thought has been the monster aluminum raidator and just the cold air running thru it.dont think its a problem but keep us informed. p.s.,send us some of that cold up here,im ready for some ice fishing and snowmachining :D

hmmm.... so is it BAD for the engine if it warms up but cools back down to "cold" on the temp guage while you're driving on the highway? That's happened to me already.
Any updates guys?

DTC P0126 Insufficient coolant temperature for stable operation
DTC P0128 Coolant thermostat problem


If these start popping up I'd be concerned

Damn you guys live in COLD weather!

sorry what are those DTCs? Are they engine fault codes? Would there be check engine lights flashing? Thanks!

Found this in the Tech Garage...
 

Where are we gonna do this?

Mods..can you combine these threads?

We're going in circles.. :)

8 is Enough...
Where in Texas are you ? I'm in Amarillo , and it can get very cold here . Why I was reading this thread , because it is going to start getting colder here next week . Hope my car warms up ! DrR

Warm up revs hunting between 1800 - 2200rpm
 

Hit < -23c -9f > this morning and while going through a long warm up, the revs bounced up and down in rythme between 1800 and 2200 rpms. Very strange! any vehicle will take time to warm up at these temps but I have never had a vehicle pulse the throttle like that. Called dealer they want to look at it said it may be " sticky throttle control ". Once the engine hit a op temp it liked, it dropped to 1100 rpm for a few more minutes and I drove off.

Did not notice anything out of the ordinary after that. When it's that cold most cars feel like I imagine an Abrahms tank must feel like to drive.


Heading to Quebec for Christmas, sure I'll be seeing some extreme temps up there this week.

8 degrees F here this morning and aftr about two miles I was starting to get some warm air from the blowers. Seems about typical for most cars I have owned all though some have been much worse. I like that the seat heaters are warming my asd long before that.

oil cooler? ... yeah.. uhh.. allright bye