My 1600 may have a blown head gasket?

Post by **Datrock** » Mon May 02, 2005 2:28 pm

Hi everyone, I recently recieved a 1600 in my project 70 srl, The previous owner knew nothing about the engine, it is not drivable yet. I got it running and now I'm experiencing instant overheating, I replaced the thermostat with a tested one, even drilled an 1/8 hole in it for safety measures, and water still boils over in the block, It's like the motor is not circulating the water and once it gets up to temperature it keeps on climbing. Or air is replacing the water to restict the flow. I removed the radiater and it has good flow, I put a garden hose up to the water pump and the water flows thru the block and comes out the filler spout. With the cooling system full and filler caps on, the top of the radiator was very hot while the bottom was still cold.
I checked the compression and it was 160-165 on #1-#2-#4 and on #3 in was 150. then squirted a little oil in each cylinder and no real changes maybe 3-5 lbs. at the most on all cylinders. The plugs on 3 and 4 did not want to come out as easy as 1 and 2 plugs. They may have a little rust under the carbon.
This kinda tell me I maybe looking at a blown head gasket on #3. There is also a small amount of air bubles showing in the filler spout. No oil in the water or vise versa. A little water out the exhaust.
My question is, do my compession readings sound normal for this problem, to me all the other symptoms show headgasket issuses. I have blown headgastkets before but it was very obvious since I was the one driving when it occured. Any input would be very much appreciated, Thanks ahead of time... Bill

TR · Post by TR » Mon May 02, 2005 2:54 pm

Small bubbles are OK, especially if you have been filling and draining the system. It can take time to get all the air out. Double check by looking for increased bubbling when you rev it. A cylinder to cooling passage communication will result in lots of air in the coolant when you rev the engine...

The other one you mentioned, radiator hot at the top, cold on the bottom may be the real problem. If fluid is flowing through it well, it should be hot at the top, warm at the bottom. Is this a known good radiator? Check to see if it is choked or take it for a boil or recore.

Good Luck! TR

Post by **Datrock** » Mon May 02, 2005 3:14 pm

TR, The radiator is not a proven one, to me it seams fine, as for the motor, while running I put the gardenhose up to the waterpump input, radiator out, and the flow from the filler spout got very hot and once I turned off engine hot water came gushing out the water pump input, so to me the pump was doing its job holding water up in the head.
I would like to take the radiator down to a shop but right now I am at a NO budject project, I do have a gasket set so changing the headgasket would not cost me anything but time.
I even looked for rags stuffed inside the water pump and radiator connections.
Could air pressure from a blown gasket be getting into the cooling system to stop the flow of water? It just seams to me the water is not circulating or it's getting replace with air from a gasket leak. I could hear bubbles excaping into the water in the overflow tank after turning off engine.
I do have a 2000 radiater I can try, If I do I'll hook up a "T" so the tranfer hose back to the filler spout wont be blocked.
Should I remove the thermostat just to see if coolant is moving thru the system while the engine is cool. Thanks.. Bill

TR · Post by TR » Mon May 02, 2005 4:06 pm

You can flush and back flush the radiator to make sure it is flowing well. Keep flushing till it runs clean. Using a trigger nozzle and pulsing the flow helps knock stuff loose, but be carefull not to blow it up! Old radiators can be weak...

Without the thermastat, it is a little easier to diagnose flow issues. One shade tree method is to provide fluid to the radiator and put the output hose from the engine into a bucket. Don't force the water into the radiator, just keep it full and see how well the engine pumps. With the output hose elevated, you'll be able to see lots of air if the headgasket is bad.

From dead cold, if the engine gets hot really quickly, the head gasket can be the one.

One word of warning, typically if the gasket is shot, most likely the head needs to be skimmed which adds to the cost! TR

Post by **Datrock** » Mon May 02, 2005 4:31 pm

TR, It looks like I'll have to tear into it and pull the head off, luckily, if needed, I have another unwarped head out in the garage. I kept a few R parts laying around. Now I know why.

Let the fun begin!!!

But first I'll do some more flushing and pull the thermostat and see how things are flowing while engine is cold, then more than likely remove the head...once the heads off the engine I'll just go from there... then when I put things back together, hopefully I'll have a closed circulating cooling system.

Once I blew a headgasket going to Reno and limped in on 3 cylinders. Next moring pulled the head and found a machine shop for milling, they also had a gasket set. The car was running 8 hours later and did not spoil the trip, even drove back thru the Bay area and up the California coast, hate to admit it almost got left out in the desert.

Do my compression readings seam normal??? Bill

TR · Post by TR » Mon May 02, 2005 4:56 pm

For an aged engine, they are great! I have not had good luck diagnosing a head gasket leak by compression checks. One way to make a guess at it is to take the compression dead cold (but cycled enough to make sure oil is about) and compare to a hot reading. Get the engine hot and quickly yank the plugs...If the compression changes drastically, something is up...Typically a warp. TR

Post by **Datrock** » Mon May 02, 2005 5:54 pm

TR, I flushed the radiator both ways and water would not back up in it so the radiator flow is good. I took out my thermostat and reinstalled the radiator and filled it and shut off car and filled again and shut off then filled again. Now I am not showing any major symptoms of the head gasket leaking.

At first there was a small amount of bubbles but they have mostly went away.There is good flow visably in the input spout and the top and bottom of the radiator is the about the same temp, hot and very warm.

Looks like the thermostat that I thought was working correctly was actually sticking. I tested it in hot water and it opened right up both times.
Also ran a wire across to the temp sensor( car is still setup for u20) and my gauge does not even go a third up the gauge.. With the filler cap on there was no bubbles coming up into the overflow tank like there was before.Plus when I turned the engine off it drew the overflowtank back down like it should.

The real test will be once I get it road worthy, I've blown the top tank seam on a radiator from having headgasket issues and don't want to do it again.Thanks again for your time and help... Bill

TR · Post by TR » Mon May 02, 2005 6:22 pm

Thermastats can be funny. I had one that checked out great, 3 months later the rubber seal turned to powder...

Drive it and see what happens, glad you didn't pull the head, eh?

Some people warm up an old motor and then torque the head. I prefer just going to mfg spec on the cold head in the same sequence that would be used for a new bolt up. Both are band-aids, but I have seen old motors with one bolt completely loose and these band-aids would save possible damage...TR

Post by **Datrock** » Mon May 02, 2005 6:35 pm

I think I got lucky, The car was a $400 deal where it did not matter if it even had an engine in it. I bought it for the body and frame, not even knowing it was a 70 SRL until after the deal, so getting the engine going is just a bonus to me... Happy roadster.. Time to go for a drive in the 68... Bill.

TR · Post by TR » Mon May 02, 2005 9:30 pm

$400 for a partial car is a great deal, especially if you almost have it rolling under its own power! Congrats! TR

Post by **Datrock** » Mon May 02, 2005 9:55 pm

TR, It's actually almost a complete car, there is a photo of it in the registery...70srl-14025. The photo is just the way I got he car, stock wheels, caps, and white walls and the strange hardtop too. All I had to do is bolt an axle in it to trailer the car home. Most of the missing parts are in boxes... Bill

steve68 · Post by **steve68** » Mon May 02, 2005 11:42 pm

don't pull the head off yet!! just because you can run a hose thru the radiator does not mean it is alright...it may jus tbe going down one side...it may come out but it might not be enough..also i had the same problem hot on top cold on the bottom and it was air in the system, i did everything i was supposed to and it still did till i took the thermostat out...i dont' run thermostats in my cars, but i also live in florida..try it with out it..it will take longer to wamup, but then you will know for sure. and i really don't know how you tested the water pump..water will go past it with pressure behind it. its not a sealed rotor, it is open and will let water pass it by.

steve

Post by **Datrock** » Tue May 03, 2005 12:06 am

Hi Steve, For troubleshooting I took out the radiator with the hoses and slowly filled the input to the water pump while the engine was running. The pump forced the water thru the block and up into the head and out the filler spout with no hose pressure involved. I just trickled in the water as it needed.

Once I turned the engine off the pump stopped thus allowing the waterin the head to backflow out the input to the pump. By the pump holding the water in the engine on it's own pumping pressure I presumed it is functioning right, or OK.

By taking the thermostat out I was able to run for over 15 minutes and no boiling over occured. I then had a more even radiator temperature too. Temp gauge read fine.

It is like what you mentioned, I believe air pockets may have been part of the problem and I was not allowing enough water to get into the block before I started it. Once I get the car road worthy I will be able to tell if the headgasket is leaking. Thanks for the input... Bill

Post by **dbrick** » Tue May 03, 2005 11:03 pm

Warning..Long winded 2 cents
I learned a long time ago to always run a thermostat. If the water flows too fast, it does not pick up heat in the engine or transfer heat as well to the radiator. Also, the waterpump requires a bit of "backpressure" so as not to cavitate/ventilate (foam up the fluid). The thermostat, in a properly running engine, only controls the minimum temperature, not the maximum. The same engine, at high rpm, WILL overheat without a thermostat if the coolant does not transfer heat properly or if the pump cavitates

If you feel compelled not to run a thermostat, you can buy a restrictor plate, essentially a giant washer, to replace the thermostat. This way the water flows as designed. Even a wide open thermostat is a relatuvly small hole.

I also read an article by Smokey Yunick about how cylinder wall wear is dramatically accellerated (3x to 4x) if an engine operates much higher or lower than about 185 to 195 degrees. Smokey knows his stuff, that is where I got most of the info on always running a thermostat after my Friend cooked his 240z at about 135 MPH on the Beltway. Hell of a ride up until the steam and bad noises started. He called a Z race engine builder, first question was "did you have a thermostat?"

steve68 · Post by **steve68** » Tue May 03, 2005 11:23 pm

thats fine and all, but saying that engines (as in all) do that is not true..every engine is different, with overbores, cams, compression and such. and smoky worked with old v8's american, not jap 4s.

thats like taking rules of thumb from a lawn tractor and applying it to your car...

steve