Underhood Temperature Issues

[ncs]

Is the radiator completely sealed to the grill/front bumper? The idea is to make sure hot air from the engine bay doesn't recirculate back into the radiator, AND that cold air coming in the front has to go through the radiator instead of bouncing off of it and going around the sides.

[RH77]

413: Good suggestion on the X-Gauge! I need to look into the SGII's extra options. I do know that the transmission case cools-off too quickly in Winter, so airflow might be OK (but Summer is another story).

IATs run about 140F in warm weather and hotter still in the blazing heat, so yeah -- I have to run premium or knock like mad. Again, it's a Winter thing. The ideal FE occurs at 100-110F. CFG has a good point -- Teggy needs a coat in the winter and shorts in the summer.

I'm gladly stuck at the home office this week, so I haven't had to go anywhere (plus a garage sale prep -- come on by for some great deals of the Great Recession!)

Further investigation: when the fans engage, the hot air blows back into the engine bay. Here's why...

< II_II X 4 |

Translation: Front of car, A/C condenser, small space, Rad, Fan, Engine, Firewall.

The A/C condenser blocks a lot of airflow. Further, air flows around the rad in stock form, with no block at all. I'm interested in the airdam. Any pics Ed?

I agree hot smell = bad. The plug wires already (and literally) blew apart over the Winter, likely because of heat stress and friction.

It's going to be hard, but I may have to go backwards in my Mods...

RH77

[Frank Lee]

My question is, is this a new thing not related to your mods ie how long have the mods been in place without the heating issue?

I'm not aware of any huge differences in coolants having more or less cooling properties. Plus, your coolant isn't very old so I wouldn't go there. Hell my '94 has the factory coolant in it and there have been no problems!

Also re: "old" battery: that same '94 has the factory battery! 15 years by my math...

I'd do the easy thing first and open up a bit of air flow. I'd also make sure the rad and xchanger fins aren't all bent over or plugged up.

If that doesn't do it, I'd test the tstat. They do go bad from time to time.

This is a long shot, but I have heard of overheating issues being caused by radiator hoses collapsing under flow- the "suction" hose needs to have a reinforcing spring in it to prevent that. Has that ever been replaced? ('94 has factory hoses too!)

[theunchosen]

The coolant is easy to do. A big misconception is higher boiling point is better coolant. . .which might be true but its heat capacity and transfer are usually more important.

Water is not likely to get boiled off if you run straight water. It absorbs heat from the engine and reaches a higher temp faster, but then it also dissipates heat to the incoming air faster as well. The radiator runs at a slight pressure increase that allows the boiling temp of water to be up from 210(212 theoretical but most of the time its 210) to about 215-220. So if you toss say 10-90 anti-freeze and water it cools much much more effectively as long as the temps stay below 212 and then it starts edging back towards anti-freeze as temps rise because water starts to boil off.

I think Water wetter is mostly an alcohol micture. The idea is its an interstitial compound that fits between the water molecules in "empty" space. So instead of just heating 8 water molecules per volume you heat 8 water molecules and 2 alcohol molecules. Also has additives that raise the overall boiling point to help out there.

[RH77]

So now there's complete flow into the air dam and I removed a small panel in the wiper area. With the fans on, you can feel air movement out of the slot.

So yesterday was a great weather day, but poor testing conditions. 50-55F and a 50 mile round-trip proved a constant 202F coolant temp at cruise (it would bounce between 198F and 204F). Cruising around town, that figure went up to 206F avg. With EOC, that jumped up to 230F and would ease down to 206-213F until the revs came up.

Frank -- that's what concerns me a bit: I haven't done anything differently than the last 4 Winters and then back to warm-weather operation. Also, I replace the hoses with new ones during the rad swap. Wow 14 years on battery, original hoses, and coolant! But the question is, how often do you drive it? (Is that the Tempo?)

I think the sensor is showing a bit on the high side. On the plus side, IATs were at the 100F range, FE was great, and the fans stayed off. No hot smell either! But it wasn't "hot" out...

So if I dump the reservoir and replace it with water, would that be a solid test? Plus, should I buy distilled water, or would filtered water from the fridge be acceptable?

On an aside, I need to upgrade the SGII to get X-Gauge. I haven't done it yet (I can't part with it for a couple weeks!)

-RH77

[theunchosen]

what!?

Filtered water for your coolant? You must pamper your car. I drop the hose into the coolant tank and turn it on lol for summer.

If you are going 100% water you want regular tap water. The amount of particulate matter that might be hard on the pump is small and pumps are pretty sturdy. Also it will slightly raise the boiling temperature of the water which would be a definite plus since your temps seem to run close to boiling anyway.

I'd recommend 90% water and 10% anti-freeze for two reasons. If you EOC and the water can't dissipate the heat its all going to boil off in the engine and the incoming water when you start back up will boil off for several seconds, which will radically drop engine temps on the water intake side, but the other side of the block is not getting any attention. Second, if you run high temps eventually the water will boil off but with some anti-freeze it lasts longer.

If you really want to(and you have a large resevoir for coolant) you could run 100% water and check it every 3 days or so.

With temps up above 200 at 50F it might be adviseable to drop any grill blocking(not your air dam but anything covering the grill at all). With straight water your radiator is going to dump more heat coming into the engine bay anyway. You IATs nothing else changed will be higher with water coolant because just as it picks up heat faster it can dump it faster as well. You might see lower IATs but avoiding high temps is important.

Most of the components have a tolerance of only about 1/1000 of an inch for their operating room and it doesn't take an enormous amount of heat to get them to expand past that. Besides the fans coming on will cancel out any grill blocking as they are draining around 1/5 of a HP.

[RH77]

Originally Posted by theunchosen

what!?

Filtered water for your coolant? You must pamper your car. I drop the hose into the coolant tank and turn it on lol for summer.

If you are going 100% water you want regular tap water. The amount of particulate matter that might be hard on the pump is small and pumps are pretty sturdy. Also it will slightly raise the boiling temperature of the water which would be a definite plus since your temps seem to run close to boiling anyway.

I'd recommend 90% water and 10% anti-freeze...

Yes, only Evian for Teggy (Is that reference outdated???)

Aside from the funny stuff, the fixes seem to be working quite well

I'm approximating a 90/10 mix. The highest temps have been 213-216F, with A/C, in town. It goes back down to 206F and all is good. Almost no fan engagement without the A/C engaged, IATs at 100-110F and expected (if not better) FE. EOC shows a spike, but still no boil off.

It's been about 150 miles with no boil-off. I'm starting to wonder if I can run 100% water and have minimal volume reduction with the inherent pressure protection of the cooling system.

Thanks guys for all the suggestions!

RH77

[theunchosen]

mmm. . .I would not go with all water.

A tiny bit of ethylene glycol goes a long way to increasing the boiling point of water. Without any glycol you'd start boiling water when your AC comes on.

You might be able to go 95% 4% and 1% whatever is in water wetter(I think its a straight alcohol but you'd have to go look at a bottle). That would get you some better cooling and maybe drop you from 213-216 with AC to 208-212 and normal of like 200 when its toasty.

I really wouldn't go 100% water unless you are willing to refill it every day. . .(use tap water, non-filtered for sure again. . .)

[Frank Lee]

Sounds like a lot of fooling around to me. Get some distilled water from Wally World or your local grocer (it's CHEAP) mix it 50/50, and be done with it for about 10 years.

[theunchosen]

Well I think thats what he had originally but the problem was the temperature in the engine were getting a little high and kicking the fan on.

Using tap water and a higher percentage allows much greater heat sink capacity for the coolant system. Unless he removes grill block and loses his higher IATs he needs something to keep it cooler.