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| DaleD | L98, they run hot. | ||
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The shop I found seems to be decent.
We were talking about how hot the engine runs. I told him the oil temp will go to 230 at about 70mph. We both agreed that's kind of hot, but not beyond what they designed it to do. Now that I'm sure the EGR is right, I can consider what next. His suggestion was to get a new fan switch, a hypertech chip and a 160* thermostat. That seems to make sense to me. I told him that PCMforless would be better if he wanted to put a chip in. He looked it up and agreed. I'm going to drive it for a while before I address this, but what do the gurus say? Is this a good approach? |
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Posted on: 2009/4/4 18:30
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| Dale1990 | Re: L98, they run hot. | ||
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What is the coolant temp under the same circumstances?
There is no reason a stockish Vette should be running that warm while at freeway speeds. When did you last flush the coolant? Clean between the radiator and condenser? Check the condition of all of the coolant lines. The fan switch, chip and thermo will do nothing more than mask the problem (if they do anything) and lighten your wallet. Both my 90 (350) and Dad's 86 (383) run under 200 on the highway with completely stock cooling systems - no chips, stock thermo and fan switches. |
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Posted on: 2009/4/4 18:41
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| DaleD | Re: L98, they run hot. | ||
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If I run about 55-60mph, the coolant will be about 200* and oil about 215*. Pushing it at 70 for an extended period results in 230 for the oil and the coolant bouncing to 230, fan on, down to 215 and back up.
Around town, coolant stays about 195 unless stopped, then it climbs. Oil will be around 200-210* Coolant system was flushed and pressure tested last July when the head gaskets were replaced. |
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Posted on: 2009/4/4 18:47
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| bogus | Re: L98, they run hot. | ||
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Grand Imperial Pooh-Bah
 
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Get used to it.
Modern engines do not over heat at those temps. They are designed to run up there. The 160* stat is the worst thing you can do. On short drives, the engine will never get up to op temp and that will speed up engine wear, not slow it. Engines running at 180 is old school. Modern engines run up there for a number of reasons. Metalurgy - the metals are designed to expand/contract and specific rates so they work best at op temps. And emissions, a hotter engine burns more efficiently. I would use a 180* stat and a lower fan temp switch. Also, check your radiator. If it is stock OEM, it mught be about toast. 20 years is a long time. Do you have the heavy duty cooling system? My 92 has a DeWitt's radiator and is otherwise stock. It runs at 192-195 on the highway and about 205 in town. You may want to switch over to Mobil 1. That's what they did in the LT1... If you are using Mobil 1, then the oil temps are about dead nuts on. Oil takes longer to heat and longer to cool... denser and all you know. In general, I wouldn't worry about it. |
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Posted on: 2009/4/4 20:25
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| dan0617 | Re: L98, they run hot. | ||
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Quote:
 You are fine. Clean out in between the radiator and condenser by removing the top radiator shroud and using a shop vac. Blow some compressed air back through the radiator and condenser. If you want a little cooler, go to a 180 stat and fan temp settings on at 198 and off at 185. Don't go any cooler than a 180 stat, wont do anything but quit making heat on cool mornings. Don't put your fan off setting any lower than 5 degrees above your thermostat temp as the thermostat temps are within a few degrees, and if your fan off temp is lower than your thermostat temp your fan will run all the time. My oil temp is 20-30 degrees higher than my water temp all the time once the car is at full operating temp. A high rpm extended run will make it 30-40 degrees warmer but just for a short time. Synthetic oils handle the heat a little better. I listed a few things you can do that will work but other than cleaning out the debris on a regular basis, none of them are necessary to do. |
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Posted on: 2009/4/4 20:32
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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| bogus | Re: L98, they run hot. | ||
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Grand Imperial Pooh-Bah
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I need to comment on oil selection in regards to engine heat.
The main difference between dino (conventional) oil and synthetic is the wax - parafin to be exact. Synthetics come from the same base stocks as does dino oil, in effect, they are both dino oil! There are other additives, of course. The wax is what breaks down under heat. It is what turns into sludge. Sometimes, it will mix in with coolant and turn into a real mess inside the engine - see Corvette Enthusiast article in the current issue regarding cooling systems. Some of the pics are scary. However, the wax gets hot, separates into oil and wax and then turns into sludge. Gnarly. Now, the other difference, at least as a function of the oils, synthetics are immune to hydrocarbon breakdown. Well, not immune, but more immune. As they heat, the hydrocarbon from unburnt fuel will separate from the oil and burn off. In conventional oil they will mingle and thin down the oil. So get synthetics... I am a big fan of Mobil 1 and Valvoline Synpower. Castrol makes a good oil, too. I suspect all the name brands are about equal, actually... I just refuse to use Quaker State... One disclaimer... back in 2002 - about now, actually - I entered into a contest on the Mobil 1 website. I was looking for pictures from the Sebring Corvette Corral and found the contest instead. I wrote a little thing about how good the oil did, how much fun the Corral was and ended up winning 2 6-packs of 5-30! Not bad, eh? Even found the PDF! |
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Posted on: 2009/4/4 21:39
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mobil1.pdf| DaleD | Re: L98, they run hot. | ||
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Thanks guys good info.
Andy, I agree with checking the radiator. Even though it was pressure tested, that doesn't mean it's flowing properly. And I definately will clean out the area between the radiator and condenser. That's been on my to do list for this year. I think I'll take the money I would have spent on the stat and chip and put it into a quality radiator. DeWitts is a good one for an L98? Is that an ebay, or Summit, or what item? I've used Mobil 1 since I got the car 2 years ago. I'm pretty sure the heads are free of build up, by virture of a head gasket/valve job. My neighbor is a retired metallurgist who worked at Ford. He said conventional oil cokes around 260*. If you're running 230* at the sensor, you're hotter in other parts. A good argument for synthetic. I had the shop change the oil when they got the sample to send for analysis. They use Amsoil. I let them put that in it, since I've heard good things about it. |
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Posted on: 2009/4/4 22:04
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| captmike13 | Re: L98, they run hot. | ||
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Here ya go Dale
http://www.dewitts.com/ The nice thing with Amsoil and other synthetics is that you can run extended oil change intervals. Dewitts has very good customer service too from what I have read at the cf. I run Amsoil in mine and have had no problems. Mike. |
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Posted on: 2009/4/5 0:45
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Mike| Matatk | Re: L98, they run hot. | ||
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As far as the radiator, Dale, I think that Dewitt's makes a quality product and has good customer service (from what I've read), but it's unnecessary in a stock application. It's also quite expensive considering your needs. When my radiator blew last summer I replaced it with one from thepartsladi and it has performed great. Something to consider for a price difference of $500 for dewitts vs $150 for stock replacement.
Matthew |
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Posted on: 2009/4/5 1:29
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| DaleD | Re: L98, they run hot. | ||
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Senior Guru
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I noticed DeWitts is pretty pricey.
Would it make sense to replace the radiator just because it's old? Seems to make sense to me. I mean, it is the orignal, and what's the possiblity it's still free flowing? You think a stock replacement would be enough, considering the difference in flow between a replacement and the existing radiator? Is there a 1/2 step, something between a stock and a DeWitts? |
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Posted on: 2009/4/5 1:47
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Whenever someone says "I'm not book smart, but I'm street smart", all I hear is "I'm not real smart, but I'm imaginary smart". |
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| bogus | Re: L98, they run hot. | ||
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Grand Imperial Pooh-Bah
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The DeWitts is a one time buy. That's my opinion. Also, if you are considering upgrading the engine, the cooling system needs upgraded, too. Consider this, also, my OEM replacement lasted about 3 years...
Point: The dearly departed jsup, in one of his online blogs, was critizing those of us who recommended an aftermarket performance radiator. I was one of those who made that recommendation and stand behind it, and this is why: He indicated that his new 427 wasn't running hot, the temp gauge was at 180-190 all the time and it would have been a waste to get such an expensive radiator. In short, he was proud of the fact he was saving $500 over the so-called "internet experts" recommendations. Well, I fully believe his engine was running at those temps. No question in my mind. BUT! It was January in New Jersey, the ambeint air temps were in the mid-30s and he was still babying the engine during the break in period. In other words, how quickly will that cooling system be overwhelmed come June, with the AC on, in stop/go on the Garden State Parkway? Or how quickly will that stock system be overwhelmed when running some hot laps at the strip or autocross? What people don't realize is that a cooling system is designed for the power you are putting out from the factory. There is a margin of error, yes, but for the most part, if the engine is putting out 250hp, you are not going to get much past about 325 before the factory cooling system starts to become problematic. And remember, jsup's engine was putting out somewhere around 450chp. This means his cooling system was being taxed by a factor of 2. That's why I got the DeWitt's. It is a two row design, versus one in the OEM radiator. It has more surface area and simply flows better. If your radiator is stock, OEM, from 1987, I would think, that at the very least it needs to be rodded out. I just don't know if that vintage is rebuildable. IIRC, the tanks are held on with aluminum fingers, and they are a bend twice and break deal... bend once at the factory, bend twice to get the tank off because you think you have one over on the man, and break the third time when you try to rebend them back. Forget it. |
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Posted on: 2009/4/5 1:56
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| BillH | Re: L98, they run hot. | ||
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The Stig Moderator
 
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Quote:
Yep My 92 runs the same temps and with a properly flushed stock radiator. Oil temps run 215 - 220 in the summer. 230 wouldn't bother me with M1. My 2000 Silverado runs at 210 all the time, winter/summer. 5.3 Vortec |
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Posted on: 2009/4/5 12:53
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| flyboy | Re: L98, they run hot. | ||
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Synthetic oil is made from crude. I didn't know that. I guess I was picturing test tubes and laboratories.
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Posted on: 2009/4/5 13:56
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| DaleD | Re: L98, they run hot. | ||
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Thanks Andy, great point. I've learned, over and over again, you usually get what you pay for. There are places you can and can't cut corners, it not always easy to know where those corners can be cut. |
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Posted on: 2009/4/5 15:53
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Whenever someone says "I'm not book smart, but I'm street smart", all I hear is "I'm not real smart, but I'm imaginary smart". |
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| Durango_Boy | Re: L98, they run hot. | ||
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Elite Guru
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I bought a DeWitts for my '77 and it's one of the best mods I made, hands down.
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Posted on: 2009/4/5 15:56
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| CFI-EFI | Re: L98, they run hot. | ||
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There is no question the Dewitts radiators are a quality and highly effective radiator. If one has a high output engine that can't be cooled by a well maintained stock cooling system, the Dewitts is the way to go. Even a mildly modified engine is easily cooled by the stock cooling system. My car has the factory installed radiator core, and it still cools like a champ. I have had a side tank replaced twice. I don't know if it was one side twice or each side one time only. But whichever, those "aluminum fingers, and they are a bend twice and break deal..." have been holding up just fine, for years.
If you have a radiator seems questionable, you can remove it and have it flow tested. The radiator shop will advise you as to whether it needs or even can be rodded out. I am not aware that mine has been rodded, but I can't be positive what might have been done while the tank was being replaced. I wasn't advised or charged for it. If a radiator needs to be replaced, and there isn't the need for the superior Dewitts, stick with the OE style from a quality reputable manufacturer like Modine, Delco, or the like. Don't be fooled by the hype of some aftermarket will-fit suppliers that brag about their two, three, or more rows of their copper/brass replacement radiators. It takes a two or three row copper/brass radiator to equal the cooling capacity of a good one row aluminum core radiator. The plastic tanks are a price compromise. All aluminum is a better idea, but unless price isn't a consideration, the aluminum core with plastic side tanks, OE style is still the best choice. RACE ON!!! |
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Posted on: 2009/4/5 17:30
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| bogus | Re: L98, they run hot. | ||
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I tried to do beat the man on the aluminum fingers... they broke... Maybe I wasn't careful enough? I thought I was being gentle enough... maybe not?
Otherwise, flow testing is a great idea. |
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Posted on: 2009/4/5 18:57
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| CFI-EFI | Re: L98, they run hot. | ||
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Quote:
??? To be honest, I had the radiator shop supply and install the tanks. My only experience is that the repairs have lasted. My radiator core has 165,000+ miles on it and it still cools very well. RACE ON!!! |
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Posted on: 2009/4/5 23:01
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| bogus | Re: L98, they run hot. | ||
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Grand Imperial Pooh-Bah
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they more than likely have the tool or skill to do it right.
Thanks for the info, tho. Even my rad shop back east wouldn't touch the aluminum fingers. |
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Posted on: 2009/4/6 1:57
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| anesthes | Re: L98, they run hot. | ||
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I run a 180* stat on mine. Fans programmed to come on at 87c (188f). Car maintains about 195 driving. Once and a while, sitting I might see a 200, but usually 195 or so is average.
Stock radiator. It runs just fine. I'm at 10:1 compression and throw 8+ psi of boost at it with no hints of detonation so I know the chambers are not overheating and the cooling system is working properly. I realize on stock L98's the factory temps are higher for emissions reasons, and some other politically backed science fiction that has been spewed onto the motoring public. If you have a stock car that is fine. If you put 6k into a race motor, I suggest you ignore the liberal tree hugging banter and keep it under 200f. -- Joe |
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Posted on: 2009/4/6 12:12
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'79 Z28. 412 CID, NP 833 transmission, 3.73 10.5" rear end. |
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| CentralCoaster | Re: L98, they run hot. | ||
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230F isn't hurting anything. You can run these oils up to 300F without issue. As mentioned, your radiator might have some debris blocking part of it.
Don't install the 160 thermostat and hypertech chip. It'll have your fan running all the time and your thermostat open all the time. Really no sort of scientific thought went into that product. The factory engineers have good reasons for some of the things they do. |
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Posted on: 2009/4/6 14:45
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| anesthes | Re: L98, they run hot. | ||
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While 160f may be too low, the last sentence of yours rings true. Take a look at the spark advance correction tables when things are hot on some of the masks. While 230f won't 'hurt' anything, it won't help either. I don't know if your doing your own tunes, but you can experiment. I've found that running around the mid 190s lets me get away with lots of advance and I don't have to run a stupid rich tune just to keep the chambers cool and out of detonation. -- Joe |
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Posted on: 2009/4/6 15:29
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| BrianCunningham | Re: L98, they run hot. | ||
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Nice thing about the DeWitts is that it's a direct fit and you can get an oil cooler.
No oil cooler on my BeCool.  |
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Posted on: 2009/4/6 16:37
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Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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| CentralCoaster | Re: L98, they run hot. | ||
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I wish that was completely true. Not a direct fit on 84s and early 85s due to the thicker a/c condenser and not available with oil cooler on 84-89. Griffin said they could make one for me with an oil cooler for $700, but it still will require putting in a thinner condenser and dealing with the R12 again. |
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Posted on: 2009/4/7 2:05
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1985 Z51, ZF6 |
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| CentralCoaster | Re: L98, they run hot. | ||
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Good point. I should've saved a sample of that Rotella I ran up to 305*F and sent it into Blackstone just for fun. My system just doesn't cool like it used to. I wonder if it has to do with replacing the 2-row Z51 radiator with a 1-row stock unit. Are the 2-rows are even available anymore? |
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Posted on: 2009/4/7 2:11
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| bogus | Re: L98, they run hot. | ||
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Even on the LT1 cars, I had to trim the fan shroud. So it was a great fit, yes, but a minor change had to be made. |
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Posted on: 2009/4/8 1:28
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| jhammons01 | Re: L98, they run hot. | ||
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Before you going buying add on things......how are the components in the cooling system.
I had issues when I got my Vette.......the thing heated up to 250°F one day in stop and go traffic.... The Water pump went bad and the radiator broke in the following months. I replaced both with stock items.....then I had to change out the old Thermostat due to it running too cool. I had to install a 175° Stat and the coolant runs at less than 210° in any stop and go. My point being, adding performance items to a worn system isn't really penny wise, more along the lines of Pound foolish. |
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Posted on: 2009/4/9 18:41
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| Flashman | Re: L98, they run hot. | ||
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Hello All,
I have had cooling problems in the past and have done a lot of research on it. If you are traveling at highway speeds where a lot of air is flowing thru the radiator and your car is running hot. Then you have a circulation problem. I bet that the more load to put on the engine, your radiator hose is collapsing and stopping circulation of the coolant. Rev the engine in neutral and watch the hose. If it collapses then you found your problem. If your car is at idle and it overheats, then you could have an air flow problem. Check your radiator cap too. The pressure of the cap, helps the system not to overheat. Also, heat creates horsepower. I would not go with a 160 degree thermostat.Too cool. These computer controlled engines are made to use a 195 degree thermostat. The least I would go is a 180. Good Luck. Joe Flashman |
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Posted on: 2009/5/21 14:02
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