I think that I might need a new water pump on my '89. The water temp rises to about 230 within about 1 minute of idling from a cold start. The ecm temp does about the same when I read with the scan tool. The lower radiator hose and heater hoses remain cold while the upper radiator hose gets hot. Have I diagnosed this correctly. I have never had a water pump fail like this. Every other time on other vehicles has been obvious with the weep hole pouring. Not the case this time. Unfortunately, I found this issue in traffic when I couldn't get off of the road. I was able to shut it down right as it hit around 280 deg. It didn't stay there long, just got there as I turned it off. Hopefully everything else is okay. A little steam came out of the overflow and there was a whistle from the heater core area under the hood. A couple of very small fogged spots inside the base of the windshield after a few minutes.

Seems like I might be in for some fun. I replaced the heater core on my previous '89 years ago. At least the breadloaf is long gone. The accessory brackets and smog crap will make the pump install fun as well.

I might go ahead and buy stock in the Yeungling Bros company because these two jobs combined will probably take a few cases.

Any thoughts on my diagnosis? Am I overlooking anything?

 

Do you have access to an infrared thermometer? I would see what the actual temp at the coolant temp sensor was. It could be a faulty sensor. If it's accurate I would put a water pump and a thermostat in it just for good measure.

It just seems to get too hot way too fast.

 

Dead cold to 230 in 1 minute sounds more like a crack somewhere to me. My kitchen oven can't even do that. I'd get one of those exhuast leak checkers for the cooling system. I'd also try firing it up from dead cold with the radiator cap off and a thermometer in the water. If the water in the radiator never gets warm, you may have a stuck thermostat.

Also, I once saw a water pump shft shear off. At low speeds it would pump some watter, but as the RPM came up it would slip at the shear point and the temps would go all over the place.

 

I don't have an infared thermometer but I was able to comapare the ecm temp with the guage temp. They were about 20 deg off, but did rise together. I will definitely replace the thermostat while I'm in there. I'm certain that it works, but I'd like to put a 180 stat in with the weather I've seen here lately.

 

Marc,

The crack theory is scary but possible. I was sitting in traffic for 30 minutes with 95 degree temps outside when this started. When starting from cold, the radiator is cold until the thermostat seems open and the upper hose gets hot. The lower hose and heater hoses remain cold. I hope that I don't need to dust the engine crane off. Hope you have a speedy recovery with the recent surgery.

Anthony

 

Might want to replace the thermostat.
See if a friend has a radiator pressure tester, it goes on in place of the radiator cap. Hook it up to the engine and see how much pressure builds up when you start the engine 0-12 psi or so is no problem, if it jumps up above 18-20 psi, look for a head gasket problem or a crack. Do you continually have to add water? See above.
Fans working?
Radiator stopped up? That new fancy anti freeze will do it?
Front of radiator blocked with debris?

 

My 85 overheated to 300 degrees (iron heads) a few weeks ago. Building a 383 to replace it.

It still runs, but the exhaust reeks and it warms up extremely fast. Goes from cold start to 200 degrees in about two minutes.

 

Never seen a cast impeller go bad, I think it would take many, many years of coolant neglect to accomplish that.
Sounds like a head gasket failure.

 

Get an laser thermometer from Harbor Freight for about $20. They work well and the one I have is within 2-3 degrees of a $250 Snap-On version.

If the engine passes the block test, then I would start by replacing the thermostat first. Much easier to do than a WP and if the 'stat is bad, that would explain the difference in temps in the radiator hoses and the fast temp rise.

With a new 'stat installed and the engine cold, remove the radiator pressure cap and start the engine. With a good 'stat and a working WP, you should see coolant flowing in the radiator as soon as the 'stat opens. Keep an eye on coolant temp at the gauge and when temps reach the opening point of the stat, that's when coolant will flow, indicating a working WP.

If you do wind up replacing the WP, it's also a good time to replace both upper and lower radiator hoses especially if they are the original ones or more than 10 years old.

 

To check the WP, remove the thermostat, a little work. Disconnect the upper hose from the rad. Start the engine. Is the pump pumping water out of the hose? You'll know right away. If it is, reconnect the hose and run the car without a thermostat. Still getting hot? Check for bad head gasket or cracked head with a block tester kit.

 

Perhaps your radiator is "clogged".

 

Thank you all for your input. I will start looking for an infared thermomenter soon. Also, after reading your posts, it seem like it is time to do a compression test and check for a cracked/ warped head or blown head gasket. I had never heard of the blue fluid for the exhaust leak test. I have a compression guage. Wouldn't that tell me everything?

 

I forgot to mention that both fans come on at the right times. I cleaned the radiator out when I installed my new AC system earlier this year. That should rule out airflow to the radiator issues.

 

I don't believe the radiator should be in the equation. As there is no or little flow on a cold start up as the thermostat is closed.

I'd say it would be good to do a compression test and leak down test.

The blue fluid test on the radiator looks for exhaust gases in the coolant. As you usually get that with a blown head gasket. You can rent the tool from Autozone and buy the blue fluid. You can find it on their mats that sit on the counter. It is called something like a block leak test.

Here's the fluid you buy:

http://www.autozone.com/autozone/acc...er=391381_0_0_

Here's the tool you rent:

http://www.autozone.com/autozone/acc...mString=search

 

I'm taking about a coolant flow clog not an air flow clog....if the upper radiator hose is "hot" then the coolant has made its way past the T stat......if the lower radiator hose is totally cold the cooled hot coolant is just not getting back to the pump to complete the loop.

 

How would the radiator cause the cold engine to get to 230 in a minute?

 

The op mentions that the instrument temperature gauge and the scan tool temperature are within 20 degrees of each other. This pretty much rules out the gauges since they are two separate gauges and the chances of both going out at the same time are remote. For those of you suggesting the op use a laser temperature gauge, what is he supposed to shoot, the block? The outside of the block has no real correlation to the internal water temperature. If the water temperature does heat up to 220 in 1 minute, it sounds like a head gasket or crack as Paul mentioned.

 

I ran the compression test tonight. There really was no leakdown more than maybe 1 psi over time on any cylinder if any. The numbers are:

1 170 psi 2 171 psi
3 154 psi 4 153 psi
5 141 psi 6 125 psi
7 160 psi 8 171 psi

Acceptable for an engine with 106k? I ran each test twice and came up with the same numbers. I let it sit for a minute for leakdown after each test. #6 is borderline, but I'd say that I likely dodged a bullet with overheating. Now I just need to figure out why it is overheating. The inside of the radiator looks horrible. Not sure how coolant passes through really. It is actually a copper replacement radiator. No signs of weeping under the water pump. Thermostat seems to open as the upper hose gets hot. I'll probably need to do the heater core as it seems to have a pin hole leak.

Here is a phone pic of the plugs in the same order as the above chart:



And plug number 8 has a bent electrode(unrelated but interesting):



When I get some new plugs in, I will continue the diagnosis. Any suggestions or ideas from this point?

 

I checked the oil as well. No signs of water.

 

If the top hose is hot and the bottom hose is cold at those high temps it's a clear indication of a coolant circulation problem and that's where I would be focusing my attention not a head gasket.

If the upper hose and top of radiator remained cold that would indicate a thermostat stuck in the closed position trapping the hot coolant in the motor. But it sounds like the thermostat is opening if your upper hose and top of radiator is hot.

The water flows out of the motor from the thermostat housing atop the intake and into the upper hose where it runs down and across the radiator to the lower hose on the opposite lower side and back up into the water pump.

1. Test the pump by removing the upper hose from the radiator and starting the car for just a few seconds with thermostat removed as mentioned. If coolant gushes the pump is moving the coolant. This isn't a totally precise test but it will at least tell you if the coolant is moving or standing still. If water doesn't gush the water pump is your problem or the upper hose is blocked. If the stat is not removed this test will be inconclusive. Do this with the thermostat removed.

I've seen new radiators installed with the plastic dust caps on the hose inlets that some come with to keep packing material out where not removed. This totally blocked the coolant to the radiator and overheated the engine.

2. Detach the lower hose from the radiator and run a garden hose through the top radiator hose inlet or radiator cap opening and see if water is flowing out the bottom outlet as fast as you're putting it in from the top. It should. If not the radiator is blocked with garbage. I always run a garden hose from top to bottom on any radiator I install to make sure it's clear.

If both of these check out then test drive the car with no thermostat installed. If everything is now fine the thermostat wasn't opening. Do a flush and put in a new one. Do not use Dex-Cool. It's garbage and nothing but problems. Stick with regular green.

The stock radiator hoses had internal spring coils that kept them from being sucked closed under high rpm by the water pump.

You can flow air through the radiator all you want. But if the water isn't moving the cool coolant in the radiator isn't getting back to the motor where it's needed.