NSW Corvettes
Technical Tips => Engines - Carbies - Exhausts - Dissys => Topic started by: Darylle on December 13, 2016, 10:34:55 PM
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Hi everyone
It appears things may have got a little hot in the engine bay today as the throttle cable casing has melted and destroyed the cable. It's location is far from ideal as it runs directly above the exhaust manifold.
I am not happy with the excessive heat in the bay including resultant damage/deterioration of the L82 hood decal.
Has anyone experienced this or knows of a possible remedy?
Thanks in advance Darylle
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Are we talking c3 here, lhd or RHD, what year.
L82 was available late 72 up
Is this auto or manual, what fan system are you running.
What temp does your cooling system run at.
Bfit
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Yes we need a little more info, from 77, GM trialed an air dam or fairing under the nose, they increased the size in 78 and onwards because it gave greater ground effect and improved cooling due to increased air flow.
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Hi
It's a '78 RHD, auto with std. clutch fan and in yesterdays heat and some traffic the temp read 200f (centre of guage)
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with std. clutch fan
Is the factory-installed fan shroud still in place?
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02 4933 3960
carters clutch and brake
119 Melbourne St
East Maitland NSW 2323.....I had the same problem not long ago,but my cable was to long and it was to close to the header pipe,just take it out and take it to a clutch and brake service centre like the one up here in maitland,when replaceing your new one try to keep it away from things that may melt the cable,but in saying that the new cables that can be made today have very high heat resistant outers,evan braided metal lines can be made and that will solve the problem,but in saying all that your engine bay should not be reaching these temps,to fix that I would suggest fan shroud,hood rubber,fan plus thermos,s,wishbone rubber mats,frnt spoiler,headlight covers that sit behind the grill and the chassis to sill plates should be there,all this is desighned for the air to flow efficiently,allso check your thermostat and the radiator,is it a sealed unit or does it have an overflow?hope this helps
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Yes very good advice, and I had forgotten about the hood seal, most important and often missing. Also if the engine is std, radiator ok, seals & rubbers ok, then it should run normal temps, if timing is out it could run hot, also even the smallest manofold leaks allow super hot gas to cause heating and hot spots. And if today is an indication of weather to come, best get on top of it. Oh! And dont let people tell you all C3's are hot in the cab, it's not the norm, and is more than likely due to holes left unfilled in the fire wall (if converted) my 78 HAD 32 holes, no underfelt or ally heat shield. Even a 1/8th hole lets in a "thermal lance" of blazing hot air once the car moves forward. Merry Xmas.
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Yes very good advice, and I had forgotten about the hood seal, most important and often missing. Also if the engine is std, radiator ok, seals & rubbers ok, then it should run normal temps, if timing is out it could run hot, also even the smallest manofold leaks allow super hot gas to cause heating and hot spots. And if today is an indication of weather to come, best get on top of it. Oh! And dont let people tell you all C3's are hot in the cab, it's not the norm, and is more than likely due to holes left unfilled in the fire wall (if converted) my 78 HAD 32 holes, no underfelt or ally heat shield. Even a 1/8th hole lets in a "thermal lance" of blazing hot air once the car moves forward. Merry Xmas.
some truth in that said above.
my C3,has good reasons to run hot , but it doesn't. on the hottest days and long runs inside the cab is reasonable.
Bfit
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Since you are in the Gong, this may be of no help, but, "Attspeed Auto Instruments" in St Mary's do speedo's made to measure a call on 9833-0055 may help you get an accellerator cable. But I'm sure the Gong would have a shop.
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Oh! - I just reread, " clutch fan" - um!!!. I once saw a mechnic test a clutch fan, sheet of cardboard in front of radiator, system at temp, stop engine, grabs fan with rag by the hand, start engine, ( yes has fan in hand, engine running) pull out cardboard, then releases the fan and watch/listen for fan to change revs - I think that was the sequence. I cant fully remember, I was busy covering my face gainst possible blood and finger bits, but he quickly proved fan clutch was rs, replaced, and it was like a magic fix. Was on an EB Falcon six. So it could also be fan clutch. If it looks oily, the special oil may have leaked out, they dont contain very much.
They are cheap enough and easy to fit,
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Thanks for the replies
The hood "seal" mentioned is the rubber tube at the rear of the bonnet I am presuming and yes it's all there including the front air dam thing.
The engine temps are not excessive (guage does not go past 1/2) The engine does have a cam ?? and given I am a new owner I do not know what other work has been completed.I am thinking of making some heat shields from that alloy stuff that looks like fish scales.
Thanks again for the replies.
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Should be seals all around the between the radiator and support, and on top of the radiator support to seal against the bonnet.
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Just to add a little more 5 cents worth, I used to work on stationary deisel sets, and one of the best tools I had was a Laser Digital Thermometre. They are quiet cheap now at Jaycars, Supercheap etc recently my 87 was running like a dog, a quick temp check on the manifold close to the head showed 2 & 8 running cold compared to the others, pulled injectors (all) and found 2&8 stuck and pouring like a tap. Just some food for thought. I'd imagine by now you have your holidays booked for corvette work only.
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Would having the headers ceramic coated help keep the temps down?
s
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VB commodore v8 cable is ideal for RHD C3 vet. perhaps look at where cable comes thru firewall. Ideal spot is to keep it as far to right on firewall as possible under guard.
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Would having the headers ceramic coated help keep the temps down?
s
Yes to some degree , ceramic coated inside and out gives the best result ,every little improvement helps.
Bfit
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Yeh, ceramic coated headers/extractors definitely help reduce engine bay temp.
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Hi all
I've made up some heat shields that appear to work great and I will post a photo when I work out how.
Thanks Steveslr for the heads up on the commy cable.
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Thanks StephenSLR for the heads up on the commy cable.
That was Sirfixalot, he knows his Corvettes.
:thumb:
s
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Sorry fixalot credit to you.
The existing cable does a big "S" through the firewall and around the engine, can these be readily converted to pull from the front giving a "C" route like a holden v8?
On another note would anyone have an approximate degrees C for the exhaust manifolds?
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Um - double check tomorrow, but I THINK it's about ~ 90 °C. I should know this, must be getting old.
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About Ceramic lagging and coatings, I've not used them but have heard they can cause heat stress in the metal causing cracks in welds and at bent points.
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Petrol engine running at full load has exhaust temp in the range of 560 deg C to 700 odd depending On a variety of factors .
Bfit
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About Ceramic lagging and coatings, I've not used them but have heard they can cause heat stress in the metal causing cracks in welds and at bent points.
That's more for exhaust wraps, rather than coatings, ceramic coated headers/extractors normally last longer. The ceramic coating holds up much better than paint, and if it's internal as well then it stops the metal from ever getting as hot. Wraps on the other hand trap both heat and moisture in with the steel. They can also be wound on too tight, restricting expansion of the pipe when it gets hot. Wraps may reduce the life of headers/extractors quite a bit.
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RHD vet you need to fabricate an L shaped bracket which bolts to the two spare bolt holes on manifold below carby on L/hand side. Then run cable out around the front & back onto carby
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That's at full tilt Bfit, on a STD C4 87 after run up to temp we have the following.
OIL - 90°C
Water - 88°C.
Readings taken at idle on the crest of each exh manifold ~25mm from the flange.
1. 150°C. 2. 189°C.
3. 202°C. 4. 223°C.
5. 226°C. 6. 220°C.
7. 218°C. 8. 240°C. So 215~230 may be normal.
I would assume 1&2 are cooler as they get more air from the fan which is cycling.
These are "as of" 10 minutes ago, But 150 & 189 could he a worry.
I have not looked at a C3 for years and I cant climb over the storage and chickens to get to it.
The C4 has metal shields around the headers, these cut "radiation" markedly, and air flow thru them takes the heat away and under the car.
I suppose at the end of the day if the oil and water temps are within spec then all is fine.
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Hi vettech
How did you get the oil and h2o temps?
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Ahaaaaaa!. It's a C4 lad. Switchable digital read outs in the instrument cluster. You can select Imp or Metric, also the four readouts can display three (3) modes each, for interest sake, 1. Oil Temp 2. Off 3. Oil pressure. Some people should have them off, because they frett over what they see, they fail to understand that an internal combustion engines parametres are always in a state of flux, changing all the time depending upon conditions - like an insurance policy!?!?!?!?!.