FWIW the plug hole is 1 1/8". They make rubber expansion plugs that are 1" that expand to 1 1/8" and 1 1/8" that expand to 1 1/4". I used the latter. When I removed two to drain the degreaser they were permanently swollen outwards, to the point where I couldnt re-install them. That was after only one day. Couldnt get a hammer in there and wasnt about to waste a few hours trying, so I just put in new ones, which I didnt tighten as much thinking maybe thatd help them be removable in the future to flush out the block. Well those two did drip over night so I snugged them up and that fixed the problem.
Took it out today for its first extended ride. Mostly seemed fine, however i did notice a small bit of water coming from the base of the rad cap neck. To the best of my ability, it did not seem to be coming from the cap at all. I watched it flow and drip a few times. Back to the rad shop it goes.
Hey Fender, I've just come across this post and am wondering if you've ever figured out your overheating problem. I have a '59 60special with what sounds like an identical problem. It's all original (stock), and I've had the radiator cleaned twice (can't get anyone to actually rod it, but it looks really clean inside and flows well, even temps. across the core), replaced the water pump twice (the first rebuilt was a pile of junk), replaced the thermostat a couple of times, removed all the block drain plugs, core plugs, water pump, and temp. sensor and pressure washed inside the block (it wasn't that dirty), and adjusted the ignition timing (the car runs perfectly). It still runs hot. The gauge runs at the far right mark and the temp. at the thermostat housing runs at 205 to 215, no matter what. It doesn't seem to matter whether it's idling, running down the road, whatever...it still runs hot. It even occasionally cools down a little when I run it hard, like accelerating through third and fourth gears repeatedly (it's a hydromatic). I still suspect the radiator, but cannot justify the cost a new one unless I know it'll fix it ($600 is nothing if it'll actually fix it)....just need to know. Anyway, any thoughts? Thanks...Mark
Hey Mark. I got married recently and used the caddy. I had to drive it about an hour and a half on back roads to get to the venue bc its not really geared to do much over 55. My temp gauge read high the whole way. On the way home it came down a little on the gauge but Im still thinking the temp sending unit is whacky. Ive had it cleaned twice and rodded once. All I can tell you is by the time you spend the money cleaning and rodding it several times it makes more sense to buy a new rad. Make sure you use the highest quality thermostat you can buy, and same with the rad hoses. Mine dont have springs in them anymore but i have heard of hoses collapsing under the suction causing it to run hot without the springs. Make sure you've got a good 50/50 mix coolant and distilled water. Sounds to me like the rad is the last variable. Make sure your fan isnt on backwards either. Should blow towards the block and suck air through the rad.
Running warm at highway speed is a indication of a radiator problem. As its ok at low speed forget about the addition of a shroud it will do nothing for your problem. Also disregard posts saying late model engines run hotter. Thats correct, but you don't have an 07 motor. Also its not a fan problem. You don't need a fan at highway speeds. Gary
Fender, Thanks for your reply......congratulations! I think I've ruled all those things out, thermostat opens properly, hoses don't have springs, but are nice and stiff and don't collapse, and the fan is on correctly. I had the water pump was rebuilt by the guys at My Classic Car Trader http://www.classiccadillacwaterpumpsforsale.com/ , after having installed a really crappy rebuild from somewhere else. They've rebuilt the generator for me also, and did what looks like an awesome job. The guy I've spoken with there seems really knowledgeable (he drives a "49 series 60 also). He says these cars don't have any real tendency to overheat. When I last had the water pump off, looking into the inlet of the pump, there is a whole lot of clearance between the impeller and the concave machined surface facing the impeller blades. Makes me think it's not circulating coolant like it should. I do see some stirring in the radiator, but it's a real judgement call....I don't know. When I asked the guy at MCCT about this (he's really kind and spoke with me at length), he said they don't have trouble with them that way, but I'm still a little suspicious and think I'll call him back and discuss it again. I gotta get to the bottom of this. I'm a professional technician in a MB dealer (19 years here), and I work on this Caddi for one of our clients (his grandfather bought it new). It's a really great original well kept car. It oozes provenance. How much it costs isn't a big deal as long as it's right, but I don't want to waste his resources. The people here http://www.mykmlifestyle.com/ have new temp. gauge sending units if you need one. They seem like possibly a good resource, I've never done business with them , but did speak with them. I found a new old stock one on Ebay, spent $60 I think. Again, thanks for the reply, if you have any other thoughts I'd appreciate you letting me know, and I'll let you know if I come up with anything. Kind regards, Mark
Thanks for the link - it sure is hard finding a 6v temp sending unit so I may go with them. I replaced my water pump all together, and put the original in the trunk. Perhaps you could buy a new one. As long as you have the correct, factory spec thermostat, you've pulled all the freeze plugs and flushed out the block really really well, you have the correct 50/50 mix, you've burped the system thoroughly, your temp sending unit is accurate, then it really comes down to that radiator. They can flow OK, but still not be 100%. If money isn't necessarily an issue I'd go right ahead with a new radiator or recore the original. Good luck
By the way, is that engine clean otherwise? Does it have gunk in the oil pan? Mine is getting cleaner with more use and oil changes, but I suspect an old engine like mine doesn't necessarily help with keeping it cool. The only true way to overcome this problem is taking things apart, really cleaning and replacing suspect items and seeing what happens. I'm willing to bet that rad is partially clogged. Also, I'm no pro tech myself - just a hobbyist who has been going through this issue as well. One more possible item: Get one of those kits that tests the coolant for the presence of exhaust gases. Its possible you have a very minor head gasket leak.
Does your car have a rubber seal at the top of the cowl, to seal the back edge of the hood to the cowl? I know some of the later cars have this seal, and if it's missing or damaged it allows the entry of air back there making for less air flow through the radiator.
Check your harmonic balancer at lower drive pulley to see if outer ring slipped on its rubber base , old balancers rubber dries out and cracks causing outer ring to move and then timing marks are off . Retarded timing causes engine to run hot . Also the vacuum pot on side of distributor must be advancing the plate inside of dist. when your cruising at steady speed or at idle , this alone will drop engine temp. around 20 degrees. Check advance weights inside dist. must not be stuck but moving freely. I've worked on many Caddys over the years and know overheating conditions well enough , you have done most of the cooling system correctly . One last item is factory called for a 160 degree thermostat. Good luck with that Caddy !
Hey- First congrats for taking the plunge! After reading everything...... Just some thoughts for the next time....... After running a flush,and you were going to be taking the rad out,and had it rodded', If there's still suspect crud in the engine= just have the garden hose in the top tank,and have the upper hose connected to a pipe or a spare hose or anything that will blow into a bucket or water your driveway.That way,whatever comes out of the block isn't going back into the rad. If a bucket= you'll see everything. Also- How hard would it be to buy a cheapy mechanical gauge to screw in to verify temps before you deem yours bad? Just to confirm before buying parts? I hate gremlins....You'll get it eventually.
This place is great...lots of good ideas, thanks to all! Hank, the balancer ideas is a good one. I haven't checked it's accuracy. I suspect it's Ok, because the thing runs so well, but no need to leave that stone unturned....I'll check it! Fender, the block is really clean. When I removed all the freeze plugs, I didn't find any appreciable gunk inside (just some buildup right behind the plugs), but still fabricated a hook shaped nozzle for my pressure washer and blasted everything out anyway, even blasted down through the opening in back of the head for the temp. sensor...the block is really clean. Also, I'm with you on the radiator. I believe it's possible for it to flow well, and still not dissipate enough heat, but it really looks clean inside after two consecutive cleanings, and with so little to cool (a small V8 with NO accessories), it seems it should have capacity to spare. My focus now is on the water pump. I removed the back of my rebuilt pump and looked around. The impeller is a stamped steel affair with 8 blades. The "face" of the blades seem way too far from the concave machined surface in the housing (approx. 1/4"), and the inner tips of them are approx. 3/16" from the opening inside the machined surface where coolant is drawn into the blades. It just looks really innefficient. In researching rebuild kits, I see one available like the one in my pump which has 8 blades and is listed as fitting '55-'62. (upper picture - this is what's in my pump) The one which is listed to fit '49-'54 (lower picture), has only 6 blades which might seem like it would flow less, but here's the thing, the 8 blade impeller doesn't fit the contour of the pump housing (the area where the inner tip and "face" of the blades interacts with the pump housing the create suction and move coolant). The impeller can't be simply pressed down farther to reduce the clearance, because the seal would be crushed . I believe this makes the pump really inefficient. I suspect that some rebuilders may install an 8 blade impeller thinking it'll make it pump more, but think it really makes the pump far less efficient. Anyway, it's just what I'm thinking....I've ordered the proper rebuild kit and am going to rebuild it myself and see what happens.... I'll keep you posted...thanks for all the great information, awesome to draw on the experiences of so many knowledgeable people. Mark
I know this is a pretty old thread but I’m curious what you saw after rebuilding your water pump? Sent from my iPhone using The H.A.M.B. mobile app
I think I would try a mechanical temp guage since your problem seems to fluctuate, which could indicate wiring problems or guage/sensor problems. Older vehicles did not run at the higher temps, that only came about with emission controls and the desire to operate the engines at higher temps.
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