3000teeth

Coming back from a fellow Rennlister's house yesterday, and after having put in a rebuilt alternator that morning, the upper hose from the radiator to the regulator housing burst.

This is a newer hose, which was replaced by a mechanic during my first inspection less than a year ago, so it's a bit surprising. Part of the break is on the hose side of the clamp that fits on the regulator housing, then it splits laterally down the length of the hose about 7 inches --making an L-shaped split. I'm hoping this is due to the clamp being put on too tight, but am definitely not sure.

The car was running slightly warm, which I figured was due to being a little low on coolant (noticed after the car was warm, and didn't think it was low enough to worry about for a short trip). I do have an intermittent tiny leak on the driver's side, bottom of the radiator, but there were no leaks after sitting for a few hours in-between my 15 mile drive there and drive home. The temp gauge was slightly above mid-point when the hose burst.

Any suggestions on what else could cause this to happen?

Thx -T

Mrmerlin

try removing the coolant bottle cap let the car run, if you start seeing bubbles in the water then you may have a headgasket starting to leak, you could also get the stuff to check for hydrocarbon in the coolant

dr bob

t--

I had a similar incident that I blame on the new hose. Better/thinner material meant I ran out of hose clamp before it was tight enough under higher pressure. Verify that your clamps are not bottomed out when they are tight. It's a simple thing but it bit me.

I use the Zerex G-05 rated coolant, which has no dye in it. Rain and cloud of steam were clear. No extra comfort in the color of the rain, however. It still took a while to get it all cleaned up in the engine baya again. I did get to verify that the low coolant level switch and alarm are working fine, a minor plus in an otherwise wonderful afternoon.

Check your clamps!

nosnow

I am with Bob on this. I think you just had a dud hose. If your cooling system was presurizing due to a blow head gasket you should have seen coolant blowing out of the overflow on the coolant tank or I would think your leaking radiator would have failed as those should be the weakest points. Makes me wonder if there really is a difference between the expensive hoses and the extremely over priced hoses!

This may have also been the source of the leak we were talking about at my house. Coolant steams out of a small hole hitting the front of the block and causing oil residue and road grime to drip looking like an oil leak. Also fits that this leak only appeared under certain circumstances. Just my .02

3000teeth

Thanks guys. Rog is overnighting me a new hose, so hopefully I'll have an update tomorrow. I'm just hoping there's not something else causing a lot of pressure in that line.

Best,
-T

nosnow

If you are worried about unequal pressure you can try some of these diagnostics to rule out a plugged radiator. Once the car is to temp check that both sides of the radiator have an even temperature. The other thing is to leave the radiator cap off and look at the fluid flow into the tank, it should change with RPM.

dr bob

This is a tough diagnostic method on the 928. The reservoir sits in the loop with the heater core and valve, so there's only circulation through the reservoir when the heater valve is open. The heater circuit completely bypasses the radiator, and in fact the circulation in the reservoir will be greater when the radiator flow is obstructed. There are some vapor/recirc vents to the reservoir, one from the coolant bridge behind the thermostat and one from the top of the radiator core, but the liquid flow from these at the bottom of the reservoir would not be noticed just by looking.


Sorry!

3000teeth

Got the hose this morning and installed it on my lunch break. Put in two gallons of coolant/water (50/50) and still didn't fill it.

When I started the shark I heard a loud "POP!" --I believe from the engine compartment, but it's remotely possible I mistook a backfire (which my car has never done). I immediately cut the engine and felt all the hoses, no breaks, no leaks --started the engine again and it ran fine.

It looks like it needs another gallon or so, so I left it and will return tonight to refill and drive it home.

Any idea what that pop could have been? Something to do with putting the new hose on, I'm hoping.

Mrmerlin

does the engine run smoothly? you might check the timing belt and see if the back of the belt looks OK I wonder if your car was hot enough and the waterpump might be doing something IE seizing? just a thought a quick look at the belt through the top of the timing cover will let you know if the back of the blet looks OK or if its burned or scratched

dr bob

3kteeth--

Fill it the rest of the way with distilled water only. For where you live with no hard freezes, a gallon of coolant should be OK. From dry the system holds something like 16 quarts; you'll add another gallon to gallon and a half of water to get things filled again.

Try not to run it while it's low on coolant. There's a mechanical seal in the water pump that really doesn't like to be run dry.

I add a bottle or two of Redline Water Wetter to the coolant mix. Seems to help with summer temps a lot.

3000teeth

Engine runs smoothly, but I'll check this out. Thx.

3000teeth

You were right-on about how much water it needed --thx. I'll also check out the Redline.

3000teeth

So I got her home --no coolant loss, and the bottom radiator hose got warm, so I think it's all circulating correctly.

The engine no longer idles at a stop with my foot off the gas, but dies. I'm guessing that a good distributer/plugs cleaning, since the whole engine was soaked, should restore this problem.

Also, the hood heat shield is still pretty wet. It's degraded to the point that when you touch it, it falls apart, and I'm planning on replacing it when I paint the whole car, so I don't want to change it yet --any advice on drying it out?

-T

SharkSkin

Wow, that "pop" sounds strange. Keeping my fingers crossed for you...

nosnow

Sorry to hear you are having more problems.

I think you idle problem may be related to a vacuum leak or a poor connection with the MAF or ignition control unit. If the engine isn't missing I doubt you will find a problem with either the distributor or plugs. just my .02

Dr. Bob, thanks for correcting me. I was thinking that the flow from the radiator would show up as it does in VW tanks.