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Discussion Starter · #1 ·
G'day guys,
Long one here.....

I bought an elco from the US and imported to Australia a while back and have still have not been able to properly drive it. The latest issue is overheating. On a cool day < 20 deg/c at idle or driving the temp gauge reads around 210-210 deg/f climbing up to 230 deg/f and the other day it after turning the car off it blew out into the overflow tank. I am currently unemployed and cannot afford to take it to someone so I am trying to figure it out myself.

The car is actually running alright, idles nice, starts right up at turn of the key. I have nothing to compare it to but feels ok driving as well.

When I purchased the car it had a computer controlled carb and dizzy, the carb needed a rebuild and it was running super rich. I replaced the dizzy with a MSD HEI unit and replaced the rochester with a 600 holley fitted to stock manifold with a redline adaptor plate. Before I fitted the holley I rebuilt it, checked float height etc. Set my idle speed with the carb off to ensure i was not over exposing the transfer slot and then fitted an adjustment screw on my secondary to adjust idle speed. I am currently about 1.75 turns out from seated on both mixture screws and its definitely running a bit rich, at this setting it's blowing some smoke. I did this to check it wasn't a mixture issue causing my overheating.

So far i've tried:
  • Connecting vacuum advance to both timed port and full manifold vacuum
  • Changed my thermostat to a 195deg unit
  • I set my total advance at 35 degrees all in which works out to around 12 deg base, confirmed with 2 different timing lights
  • Checked for intake leaks and vacuum gauge shows good vacuum. Needle holding and behaving as it should. Very slight leak at secondary shaft, added some bees wax around the shaft to see if that was causing lean condition, no change.
  • I have flushed the radiator with a flush kit a few times and then the entire system was rinsed out until there was no more brown water, fresh coolant added. no leaks anywhere.
  • Bled the cooling system with car up on a hill, heater on
  • Replaced the thermo fan clutch with a heavy duty unit. No change.
  • Fitted Iequus aftermarket mechanical temperature gauge and sensor fitted next to #1 spark plug, original gauge was disconnected by previous owner
  • Compression tested each cylinder, can't recall exact reading but it was good from memory. little variation.

What i'm not sure about:
  • With it previously running very rich I wondered if the cat may be blocked, could that cause it to overheat? The car can legally have the cat removed here.
  • EFE valve has the diaphragm removed, its not stuck and is free to move, that being said it wasn't wired open but have confirmed it is open when it's been overheating
  • Valve on heater inlet hose has no vacuum attached, my understanding is this valve only locks when vacuum is applied from AC on max? So shouldn't make a difference.

I am at a loss here, i figure the exhaust showing rich would indicate it's probably not a mixture issue. Timing is correct so likely not a timing issue, starts and runs fine. Figured maybe the gauge was wrong but with it overflowing into overflow tank it's definitely getting too hot. The passenger side valve cover is too hot too touch while driver side feels hot but can still touch.

Anyone have any other suggestions of where to look here?

Cheers
 

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hmmmm, you've done a lot of stuff but I think you should start back at the basics and concentrate solely on the cooling system.
-original or new radiator?
-you changed fan clutch. why not go electric fans?
-do you have a laser thermometer to measure coolant temp as it enters radiator and exits radiator?
-I see no mention of the water pump, have you changed it? it's possible the impeller is gone
-how many miles on engine?

remember, the radiator is a heat exchanger. if it's not pulling enough heat out of the coolant then you have an issue there.
if the coolant coming out of the engine is too hot, then you may have issues in the block itself with garbage fouling the cooling jacket.
if your valve covers are hot enough to burn that's probably way too hot. which means your oil is probably running too hot because the coolant is not pulling enough heat out of the block.
 

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Discussion Starter · #3 ·
Cyberray, thanks for the help.

Original radiator, seems to be in reasonable shape, fins are in good shape, water was brown when i got the car but after a few flushes and running its staying clean.

I changed the fan clutch to another unit just from reading and the fact its basically a stock motor I figured the stock setup would be sufficient.

I haven't changed the water pump, i can't see any leaks. Is there a way to check it's functioning correctly?

Engine has 65,000 mi on the clock. It's in pretty good shape overall and i believe it to be genuine.

Funny, in between my first post and now my neighbour came out with is IR temp gun. The gauge in the car was showing around 210 at this point. The heater hoses were showing at about 205 deg/f. Lower hose was showing at 96 deg/f but the top radiator hose was only showing around 145 deg/f. With the block sensor showing 210 the thermostat should have been open and that top hose should be the hottest hose at that point but it wasn't. Very strange, I could hold my hand on it just fine, i was holding at the point where the hose it at it's highest to clear the belts, down lower towards the rad it was a little hotter and the thermostat housing was showing closer to 205 deg/f. Considering this is a new thermostat too it should be opening. I had the same overheating issue with the old thermostat I replaced too so unless they are both bad i figure it's probably something else.

Makes sense what you're saying there, what would you suggest i do next?
 

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I am in Cyberray’s camp. Before it is to hot you should be able to remove radiator cap and check flow. More flow when stat opens. If not, remove top hose and keep water in radiator just below upper hose connection. Impellers deteriorate.
Tom
 

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As a long time owner of an ‘85, I agree that you’re missing something. If it truly has only 65,000 miles, that’s likely an original pump. The brown watet is rust, meaning the the cooling system hasn’t been maintained (and likely had tap water, not distilled, in the mix). I too bet it’s your impeller on the pump.
However: 205-210 shouldn’t be causing problems. At most it should gurgle into the overflow and suck it back when it cools. If it’s not ‘behaving’ you may have an air leak into the system (like a bad radiator cap). It should not blow off hoses or vent steam.

These cars cool great with working ‘aircon’ in Georgia heat in stock trim; they shouldn’t need additional help (electric fans, water wetter etc.)

If you’re going to keep the 305 mostly stock, I’d have the original carb rebuilt and put fresh parts in the original dizzy. Lose the catalytic converter, though; they’re restrictive!
Patrick
 

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Good advice by all, if it was mine I would replace the radiator with a 3 row unit and replace the water pump and I would swap out the heater core as well since the cooling system was neglected. I would do a flush one more time and be certain to drain the engine block by removing the two drain plugs on the side of the block in the middle of the block just above the oil pan. Now I would bet that you will have to punch through the corrosion (the inside of the block will have a rust/scale build up just behind the plugs which are normally 9/16 socket to remove these plugs). With the block and drained and you have installed the new water pump and radiator (and I would replace the heater core) replace the drain plugs and remove the thermostat and premix the coolant and add coolant in the radiator and after about a 1.5 gallons or so you will see the coolant at the opening of the thermostat. This will ensure you do not have any air bubbles or pockets in the cooling system, I keep the coolant about a 1/2 inch below the thermostat housing, install the new thermostat and gasket and then top off the coolant, no air pockets, works every time. At a minimum replace the radiator, the rust water you stated has most likely corroded the inside of the radiator and clogged some or most of the tubes and that is why I would replace the heater core as well if the radiator is junk so is the heater core. Good luck!!
Matty man
 

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For a simple test, get your radiator cap tested at the local auto parts store, or just replace it. They go bad over time, and will not hold pressure, so temp's rise, and hotter water will bubble thru to the overflow tank. Might save you a ton of money chasing "stuff".
 
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there is no way to check the water pump impeller without pulling the water pump. you mentioned: 65k miles, brown water, seems all original.....

I wonder if the previous owner even had distilled water in the system and that accelerated the rust? which then increased the amount of rust junk in the cooling jacket?
I'd do what Matty mentioned above, "be certain to drain the engine block by removing the two drain plugs on the side of the block in the middle of the block just above the oil pan "
the only thing I don't know is how hard it would be to scrub those passageways with a bottle brush with the engine still in the car, or to even insert new freeze plugs. Matty? and if you do that definitely do the water pump passageways on the front
 

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Discussion Starter · #10 ·
Thanks everyone for the feedback.

PBR,
At the moment it does seem to be holding pressure, doesn't seem to be any hissing or leaks around the cap. Although when it's getting hotter it has been blowing out into the overflow all of a sudden and then has been drawing back in as it cools. So far it hasn't climbed over 230f. I just really want to be able to rely on this thing as I'm planning on using it as my daily driver once I sort these issues out.

Ideally I would have kept everything original on the car, problem is these cars are rare in Australia. Never delivered here, parts are hard to find or expensive to ship from the US. With money being tight for me the cheapest option was to run the holley, lot's of guys here can work on them and it's easier for me to work on that the rochester.

Matty,
Ideally I would replace the radiator but I just don't have the cash at the moment, it would need to be shipped from the US. I want to be sure of the issue before I throw too much money I don't have at it. I had considered maybe having the stock tank dipped or rodded. Could be an option failing this water pump fix. I'll definitely follow your process for eradicating air in the system when I get everything back together. Do I need to replace the freeze plugs if they are removed can they not be reused? I am not familiar with them.

A water pump replacement seems to be the next order of business and I can get the cash together for that. I have found these 2 options on ebay here in Australia, not too expensive. Leaning toward the cast iron unit.
https://www.ebay.com.au/itm/174587384124?hash=item28a638113c:g:t50AAOSwGB1f9-Vj

Water Pump Small Block Chev V8 283 305 307 327 350 400 Short Cast Iron W2593 | eBay
 

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Thanks everyone for the feedback.

PBR,
At the moment it does seem to be holding pressure, doesn't seem to be any hissing or leaks around the cap. Although when it's getting hotter it has been blowing out into the overflow all of a sudden and then has been drawing back in as it cools. So far it hasn't climbed over 230f. I just really want to be able to rely on this thing as I'm planning on using it as my daily driver once I sort these issues out.

Ideally I would have kept everything original on the car, problem is these cars are rare in Australia. Never delivered here, parts are hard to find or expensive to ship from the US. With money being tight for me the cheapest option was to run the holley, lot's of guys here can work on them and it's easier for me to work on that the rochester.

Matty,
Ideally I would replace the radiator but I just don't have the cash at the moment, it would need to be shipped from the US. I want to be sure of the issue before I throw too much money I don't have at it. I had considered maybe having the stock tank dipped or rodded. Could be an option failing this water pump fix. I'll definitely follow your process for eradicating air in the system when I get everything back together. Do I need to replace the freeze plugs if they are removed can they not be reused? I am not familiar with them.

A water pump replacement seems to be the next order of business and I can get the cash together for that. I have found these 2 options on ebay here in Australia, not too expensive. Leaning toward the cast iron unit.
https://www.ebay.com.au/itm/174587384124?hash=item28a638113c:g:t50AAOSwGB1f9-Vj

Water Pump Small Block Chev V8 283 305 307 327 350 400 Short Cast Iron W2593 | eBay
I can't vouch for the quality of those pumps but I can price compare them to the US.
$90 (AUS) = $70 (US)

this water pump is $56+tax (US; $71 in AUS) but you can get them discounted with an online purchase
Advance Auto Parts - Down for Maintenance

so your prices for the water pump are not that far off. I'm not sure I understand why it would be hard to get some parts as these are SBC and GM made millions of these things, even down under.

Freeze plugs have to be replaced if pulled out. But from your mention of lack of familiarity, I think I'd recommend having a mechanic do that if possible, but watch the videos below so you know what we are talking about
 

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Does your thermostat have a small hole in it to pass air pocket bubbles up and out of the cooling system? If not, drill a small hole in it to "burp" this air out.

Rick
 

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Try this for a water pump $29 US dollars. good price. They say they ship to Australia.
Gates Water Pump (Standard) Water Pump fits Chevy El Camino 1977-1987 54SPZT | eBay
I bought a Gates brand water pump off of Ebay about 2 years ago. Works great. I have an 84 with the 305. I never see my car go above 200-210. Most of the time a bit lower as I am driving. I am in SE Texas. 90's temp with high humidity almost every day. Stock Thermostat, 195 degree. Stock radiator cap ACDelco 16psi
If you have a radiator shop locally see if they can boil out your radiator.
 

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Matty,
Ideally I would replace the radiator but I just don't have the cash at the moment, it would need to be shipped from the US. I want to be sure of the issue before I throw too much money I don't have at it. I had considered maybe having the stock tank dipped or rodded. Could be an option failing this water pump fix. I'll definitely follow your process for eradicating air in the system when I get everything back together. Do I need to replace the freeze plugs if they are removed can they not be reused? I am not familiar with them.

A water pump replacement seems to be the next order of business and I can get the cash together for that. I have found these 2 options on ebay here in Australia, not too expensive. Leaning toward the cast iron unit.
https://www.ebay.com.au/itm/174587384124?hash=item28a638113c:g:t50AAOSwGB1f9-Vj

Water Pump Small Block Chev V8 283 305 307 327 350 400 Short Cast Iron W2593 | eBay
[/QUOTE]

Hello Panama,
I would do what you are doing then, swap out the water pump and if you still have issues then I would remove the radiator and have it boiled and see if the can remove one side of the side tanks and rodded like you stated. Just wondering can your local radiator shop make a new 3 row radiator any cheaper or re-core your original radiator? You don`t have to use a 3 row I just prefer them here in Ohio cause it can get hot here at times, 100 degrees plus F.
Far as the freeze plugs once you remove them they lose the crush they have and cannot be re-installed. They can be a real pain in the back side to remove especially the two on the side of the block the rear ones. Keep pluggin` away you will get it,,
Matty man
 

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Discussion Starter · #16 ·
Thanks for the help guys, I appreciate it.

Funny thing yesterday, first of all i removed the thermostat and replaced the housing without the thermostat in place and top hose connected running into a bucket. Started her up and had really strong flow from the water pump. As mentioned above the pump isn't showing any leaks and also theres no play in the shaft. Considering it seemed to be pumping well and it's showing no signs of damage is it still worth replacing you think? I guess as mentioned the impeller could have deteriorated which wouldn't be diagnosable externally.

After the water pump test I dropped the coolant out, removed the new thermostat I had purchased and replaced it with the old thermostat that was in there, I used the method described above to top up until 1/2" shy of the thermostat surface and then replaced the gasket and housing. Topped up the rest of the radiator and started it up. I couldn't believe it, the thing held just shy of 195/f for a good 20 minutes or more idling. Something that has no happened at all since this problem reared it's head. I went for a drive and came back and it started getting back up to the 210-220 mark. Strange because it was behaving as it should at idle for quite a while. Previously it would climb straight to 210 within that same amount of time. I did however notice a small leak in my heater hose when i moved it from behind the hose clamp during this process i'll replace that today and try the process again.

Cyberray,
Holden is the the chev equivalent you could say over here. Problem is stock parts for older models seem to be hard to come by. Holden parts department stocks some AC Delco parts but not much. I can always buy aftermarket pricey brands like edelbrock from performance shops but then they price is considerably more.
I had a look at those freeze plug videos, I think I could handle the job. Do you think it's something worth doing at this juncture? Or should I stick with other easier things first. The coolant dropped yesterday was still green with no signs of rust.

Vinny,
Cheers, I'll have a look at the Gates brand and see if they have a stockist here in aus. Failing that i'll order from the states.

Matty,
I'll contact a few rad shops today and see what i might be looking at to get the thing boiled and/or rodded. I guess at the end of the day, even though as mentioned above the pump seems to be functioning if it is indeed the original pump it's going to go eventually even if it's not whats causing my problem at the moment. I might just have to pull the trigger on it.
 

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Converters can and do clog. You said you are allowed to remove them. I would remove it and this will eliminate one possible cause. Virtually no cost to you. They usually don't clog "a little bit", they clog enough to really change performance. Be that as it may, it doesn't mean that yours isn't clogged a little.
One other thing to check is the pulleys. You never know what someone could have done. The water pump should be turning about 30% faster than the crankshaft.
Remember, your El Camino came from the factory and didn't overheat. Adding aftermarket stuff like electric fans and big radiators may fix the problem, or do they just hide the problem. Stock parts should be just fine.
 

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If it cools fine at idle but overheats when driving, that sounds like the radiator being clogged, not the water pump. (That rusty brown stuff may still be in there).
Patrick
 

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Surprised I haven't seen this recommended yet but have you looked at radiator dimensions comparatively against say an older Holden with a SBC? Here in the states a 4th gen Camaro or Firebird has a similar sized radiator that would work in a G-body. I'd imagine an older Monaro or something might be similar?
It's pretty cool you had a different kind of Ute imported to Australia. I've also got an '06 Pontiac GTO (Holden Monaro) and I'd love to get my hands on a VZ Ute to match.
 

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Discussion Starter · #20 ·
Well, I'm back with an update.

I ordered a new water pump. It arrived and is the right fit. Took the old one off and removed the impeller cover to check it's condition and it's clean as a whistle in there. I do believe it to be the original pump but it's in good shape. No play in the shaft or the impeller itself. This issue adding up with a new fan clutch and water pump i'm up to $300 so far.

I used this opportunity to check the fins of the rad for debrit and it was clean, the inside of the rad actually also looks pretty clean. I really don't want to drop a few hundred more on a radiator and still have the issue.

Is there something else that I could be missing here? I wondered if maybe my harmonic balancer had slipped and my mark is off. But the car starts easy and runs well. Idles well.
 
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