View Full Version : 94 SLS I seem to be on a losing streak!

Rob Benham
03-15-06, 05:15 PM
The story of tidying up my radiator job is too sad to tell. But suffice it to say, that a car that has for two years flopped between 199 and 201 203 going up hill on a 100 degree day.

Suddenly it started to hunt about from 200 - 214. At 70f outside air.

Okay, I know the figures, but I'm one of those that likes to keep the temp stable in my old car. Today it went right through the 223 yep, the fan ran at half speed, and on to 227 when the fans spun up to full speed. Unfortunately, this did not stop the rot. At something like 255 the system went into A/C compressor shut down, and "ENGINE HOT".

Another couple of questions if anyone is genned up on this.

Is this likely to have distorted/cracked the heads? Or opened up the prospect of head gasgate problems soon?

Most of my efforts were outside the company that sold me the new rad, but in the end, having cut the center out of the stat, and filled it and boiled it a couple of times, (it would rocket to 210) I decided that it must be the pump.

I was a few miles from home and as one last ditch attempt to get home, I hosed water under pressure into the engin and top hose. I set out expecting to take hours getting home...to my astonishment, it ran 180-195 (no stat still)

Although an air pocket may be the answer, this Chinese rad is not the one I wanted, but I'm about as far South as you can get, and the ordered one was incorrect when the box was opened. I seem to be on a losing streak!

But is it likely that a poorly made rad could have kick-started my problems? Or....

Can the entire problem just have been an air pocket? (It had never been a problem filling over the last 2.5 years.) If not, any other ideas? Rob

03-15-06, 10:40 PM
There's a bunch of stuff to check. Purge line, water pump drive belt, radiator cap for starters.

Either a coolant check for byproducts or better yet a cyl leakdown test for bad head gaskets.

03-15-06, 11:28 PM
Pump unlikely. It'll either work or not. Purge line's common. I got something stuck in mine once and ended up taking it off on both ends and running compressed air through it at 40 psi to clear it!

03-16-06, 10:47 AM
I would not be too worried about cracked or distorted head, but I would be concerned about the head gasket. With the engine idling (cold), pull the purge line at the surge tank. You should see a coolant flow or at least spitting (full flow at higher RPM). If not, that may be your problem, clear it out and be sure the supply port is clear as well. If that is ok, put the stat back in, check out the Chineese radiator and then run a cylinder pressure test.

Rob Benham
03-16-06, 04:49 PM
Huh, I see that the spelling gasgate is English...from about the time of early steam trains. Wondered where I got if from.

It's looking a bit bleak. Based on my experience with a Toyota Supra, I'm getting the feeling that it might be a head gasket.

EDIT The pump seems to be working, but is there no chance that the blades are not corroded? one that i looked at yesterday had almost no blades left, but it still turned okay. IT WAS NOT A CADDY ONE HOWEVER.

I do not have the service manual cos I'm too old to get involved with heavy stuff these days. Also, the car is quite nice, but no collector's specimen. However, the engine and gearbox were nothing short of perfect. Never any oil or water top ups, and super smooth and 27 mpg highway.
The engine was worth more than the car.

Now, having cleaned out the purge line, and generally blown water into every large and small hose I can get at, it ran without stat at 185 for around ten miles. Just when I thought all was well, the temp went up to 208-- 210 and stayed there. Fans on or off made no difference!

It is that time of running that makes me think it's the gasket, just about the right time to let metal expand and allow leakage. But I will run through the items that you'all have posted, and make sure that I'm not scrapping a good car for no reason.

Thanks for your help, any further ideas would be welcome Rob.

03-16-06, 08:09 PM
Cadillac's water pump is hubless. It's an interesting design and very efficient. I don't know how it would loose blades. It would be very strange, probably leading to the whole thing flying to pieces inside.

Rob Benham
03-16-06, 08:36 PM
The strange thing is that there was no problem at all until I changed the rad. One heck of a coincidence.

I did put three tablets of ‘stop leak' in the TOP HOSE, but had turned it into a brown liquid before putting it in. I couldn't have blocked the new rad...Er, could I ??

At around 210f with the cap off, the water bubbles out of the filler cap, splashing about a bit. It seems rather too low a temp for a boil up, but I would have thought that the bubbles were too big to have been caused by gasses getting into the water. There is no small bubble foaming in the tank.

The purge line, even at 2,500 rpm, would take 20 secs to fill up a cup. The purge nozzle is clear.

I noticed a very slight roughness at tick-over this evening. All adding up, but I haven't pulled any plugs yet.

There is no doubt that giving it a quick, almost a WAT, causes the temp to rise shortly afterwards. Again it is though gasses are leaking when it is hot and with high pressures.


03-17-06, 02:12 PM
At around 210f with the cap off, the water bubbles out of the filler cap, splashing about a bit. It seems rather too low a temp for a boil up,

In your other post you mention running plain water... Are you running 50/50 coolant/distilled water or plain water?? Plain water boils at 212...just like you report in your comments above. Simple. Exactly what it is supposed to do. Fill the system with the correct 50/50 mix of coolant/water. The coolant increases the boiling point significantly as well as preventing freezing and corrosion inside the system. Never run the system on plain water. It will not function correctly at all.

It is perfectly normal for the coolant temperature to swing a bit. Sitting at idle the temp will go to 225 or so before the fans even turn on so that is perfectly normal. Fill the system with the correct mix, put the cap on and drive it for awhile and see if it is overheating...i.e...getting above 245-250 and/or boiling over. If it is then you have a problem. If not, then you are working yourself up over nothing.

Rob Benham
03-17-06, 02:14 PM
Well I'm down to clutching at straws.

Pump belt is good, and the pump can be seen spinning.

Purge line is clear, as is the nozzle on the tank...I'm also purging overboard to prove the point.

Just in case I blocked the new rad with Bar's, the guy at the rad shop has offered to check the flow on the new rad...he says to do this he would have to pull the ends off. As mentioned, I put the Stop leak in as a liquid, though in the top hose.

If it is improbable that the pump should fail in a way that would make it "half work", then it would seem that this is pumping, or it wouldn't be putting water out of the purge line... right? Is there any other way to tell if the pump is really belting the water round?

Everything seems to be happening too quickly for head gasket, but as I have asked on a parallel thread is it wrong to test with plain water...how much difference could it make?

I know for certain when I first got this car 2 years ago that it would run without thermostat and on plain water at 175 ish, while on test. Since then it has been a dream machine. (30k miles.)

Thanks again for all the help so far Rob

03-17-06, 02:23 PM
Yes it is wrong to test with plain water. Plain water boils at 212 as you noticed. It will create steam pockets inside the engine even at lower reported temperatures and then the water pump will injest the steam pocket and stop pumping until it can purge itself of the air/steam. Put the correct 50/50 mix in the system.

Rob Benham
03-17-06, 05:58 PM
That would seem to fit the scenario fairly well, I can't remember what time of year it was when I ran it on water. It was only for a day or so, while I assessed quite what I had paid too much for.

I purchased the car from a young mother of two kids. She said she had been left, and had to sell the car. I said way back, that she was probably a world-class sales person. The tires were at 76 psi to stop it pulling, and the fans had been hot-wired to counter the almost nonexistent water-pump belt and bad stat. To my astonishment, it ran like a dream after sorting the problems.

This PM the guy opened one end of the rad, and washed out quite a lot of Bar's...but not enough to count for the problem. I still feel that I should look into the pump housing while everything is out of the way, and the water is empty.

EDIT I've just had a good look at the pump, and of course it's driven from the other side so just looking, will I hope be easy.
Can the same pump be taken out and put back without destroying the seal?


03-17-06, 07:42 PM
Theoretically you could put it back, but you have to make sure the seal's intact first. If you destroy the seal, of course you can't. If you don't destroy the seal, it should work.

Rob Benham
03-17-06, 10:42 PM
chevelle, sorry didn't really reply directly.

There is a parallel thread (coolant fans) running in which I recalled the thread about keeping the temps stable. I went with the lot that liked stability of temps.

The car went for 2 ½ years with scarcely a 3 degree fluctuation. It is the sudden change that worries me, more than the top temps. A bit like having a mother in law that suddenly stops nagging. You wonder why!

03-18-06, 02:19 PM
The temps will normally fluctuate quite a bit during normal operation. If they weren't fluctuating before then I suspect something in your driving schedule changed or just the ambient temperatures...or the time of the year....cause it to start moving a little. It is normal for the coolant temps to swing so I would suspect something odd if they DIDN'T.

When the AC is on the cooling fans will run all the time (generally speaking) when you are at low speeds and idle. This will pull air over the radiator and keep the coolant temps a little more stable some times. When the AC is off then the coolant fans will not run unless the coolant temp is above 225. So....just turning the AC off in moderate weather could cause the coolant temp to start to fluctuate. Perfectly normal.

Fill it up with the correct coolant mix and drive it. See if it over heats. Put tape over the temp gauge. You are getting upset over nothing.

Rob Benham
03-18-06, 04:52 PM
It is normal for the coolant temps to swing so I would suspect something odd if they DIDN'T.

Thanks chevelle, (see my other post re the stop leak) yes you may have hit the nail on the proverbial head there. Although my work entailed staring at gauges for endless hours, it may be that the incredible stability over the last 2+ years, was in some way false.

I feel that I have taken in to account most of the parameters like ambient temps etc, and the A/C always did cause a 1- 2 degree RISE in temps, I assumed because of the load and then the warmer air from the front rad. (Held up at lights it would of course serve to pull the temp down.) But it was always the same..for 30k spot on. In the Tx hill country, there would be a rise of as much as 5 f on a warm day. Warm here is 90+

Today, it seemed to get hotter as I went into mild traffic. After stopping at a store, the gauge gave me a ??? Somthing like "Coolant Hot" this quickly went down when I moved.

For all the world, it is though part of the engine is not getting cooled properly. Could this be the reason for the 2 gal max that I can ever get in?...see other thread.

Tape the gauge up.. He he....that'll do it.