# 68 GTO fluid loss/overheating issues



## djoslin (Jul 30, 2012)

I have a 68 GTO that has a 67 400 engine (XW code). There are no fluid leaks under the car but if I don't start it almost everyday, I find the radiator fluid is down about 3 inches from the top when I do. When I drive the car it starts to heat up. I was getting water in the oil and had the radiator system pressure checked. Nothing showed up but I kept having fluid loss. I had the heads (061) removed and checked (magnafluxed ). No cracks but the head gaskets did show that they were leaking. Heads were checked to make sure that they were straight and reinstalled. Not as much fluid loss as before and no sign of water in the oil.

I now am getting a lot of water coming out of the passenger tailpipe and some from the driver's side when the engine is first started. It blows black water until it heats up. The exhaust throws enough black water to make marks on a driveway. The fluid level is starting to drop to the lower level so that I have to add fluid weekly.

Can the engine block have a crack that only gets larger when the motor gets hot? I don't see the amount of water in the oil like I did before. The oil was a very milkshake color before and now it is just dark black like it is running too rich.

No leaks on the ground and none that I can see on the engine.

I am at a loss to know what to do next short of having the engine torn down.

Any suggestions will be appreciated.


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## pjw1967 (Mar 10, 2014)

Way over my pay grade here, but it sounds like 2 problems. I get the black water at start up on my '67 WT. We have high humidity here, so there is condensate in the exhaust system. At start up, the engine blows it out of the exhaust pipes, mixing with the carbon in the pipes. Actually stained the concrete in the garage. Re fluid loss, are you running hot? I installed a '66 washer bottle next to the pass side of the radiator that collects the overflow when the engine gets hot. In theory, the fluid should get sucked back into the radiator when it cools down. You don't mention replacing the radiator cap. A faulty cap can cause the problem too. Hopefully you'll get a lot of replies with other poss causes and solutions.


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## Rukee (Feb 8, 2007)

Do you have an overflow bottle? If not then the lower level is normal.


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## djoslin (Jul 30, 2012)

Thanks for the remarks about the condensate in the exhaust system. That is what I thought but just needed someone to tell me that their car does the same thing.

I don't have an overflow tank and I understand that can help with fluid loss. I did replace the radiator cap. I probably will get a washer tank to see if that helps.

The car will run hot when I don't have the fluid almost to the top of the radiator. This seems strange to me since most people tell me that a cold car should show the fluid about 2-3 inches down in the radiator.

My main concern is where the radiator fluid is going. I just hate to look at the levels and see it down in the radiator. If that is normal, great . I can live with keeping a gallon of antifreeze in the trunk and checking levels before I drive the car.

I did not mention this but the papers I got with the car indicated that one of the former owners was concerned enough about this that he had a machine shop check the engine for cracks. The report from the machine shop was that the block looked OK. I guess this has caused me to be overly sensitive to fluid loss and overheating.

Thanks for the responses. If anyone else has suggestions, I would appreciate them.


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## geeteeohguy (Feb 2, 2008)

Black wet water on the ground for the first few minutes is normal for these cars. Condensation. Not an issue at all. You need to pressure test your cooling system and you can get a block leak checking outfit at NAPA to check for a cracked block or heads, etc. Personally I feel that your engine is probably ok, but you need a new radiator or fan clutch, or both.


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## djoslin (Jul 30, 2012)

Thanks for the information. I recently installed a new fan clutch and the fan is sitting about half way inside the shroud. Looks like a new aluminum radiator is my next purchase!


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## PontiacJim (Dec 29, 2012)

What do you call heat up when you drive it? What temp? Where is the temp sender mounted on the engine? Has the sender ever been replaced? 

The factory manual for my '68 says that the water level should be 1" below the water neck when hot and 3" below the water neck when cold. So if you keep filling it up full when cold, the excess anti-freeze will be sent out the overflow tube each time the engine heats up to temperature. 

You had the heads checked/magnafluxed but you did not say the block was done. You could have an uneven deck which the heads seat on. This can happen, just a thought.

Are you sure the engine was assembled with the correct length bolts? If someone replaced the factory bolts with ARP head bolts and ordered the wrong kit, ie Ram Air IV head bolt kit, you will have head bolts too long and they will bottom out before they tighten. Another tough water leak find is if there was any oil built up under the head bolts down in the block where the threads are found, the excessive oil will build pressure from the heat of the engine and literally have enough pressure to crack the block area where the bolts thread in. Water will seep in from here and is extremely hard to detect without magnafluxing for it. My machinist said he has had this experience a time or 2 where others could not find the water leak issue and this is where it was coming from - he found it.

What temperature rating is the thermostat? Have you tried a 160 degree? Thermostats lately don't seem to be the quality they used to be. A new one can go bad in a few weeks - it has happened to me on my Toyota daily driver. 

Have you ever had the timing checked? Timing can have big influence on engine heat/water temp.

Where your heads fitted for hardened seats by chance? This is a very precise job and if done incorrectly, the machining process can break inot the water passage. It may not show up when cold, but when things expand, there COULD be a problem. I have never know anyone who has had this happen, so I am just throwing this out as a possibility if your heads have had this done to them.

It could be as simple as a new radiator, but I would have thought this might have showed up in the pressure test? It has been recommended here before to get one of those inexpensive laser type temperature readers and take actual temp reading off different parts of the engine to diagnose if you have any hot spots. If one side of your radiator is hot while the other cold, you know it is a radiator problem. Test the heads, engine block, top water hose, bottom water hose, etc. and see if you get any really large differences. This may be quite helpful in finding the problem or confirming that your engine temp is OK and your gauge is not.

Could be a bad water pump. 

Not trying to discourage, but you can see that there could be a number of things wrong here. Do one check at a time and don't think big as you may not have that big of a problem as it may be a very simple fix -you just have to isolate it. The temperature laser gun would be my next investment before spending "hit or miss" money you may not need to. Most auto parts stores carry them. Bottom-line pricing on Electronic Specialties - EST-35 at ToolTopia.com :thumbsup:


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## djoslin (Jul 30, 2012)

Thanks for a lot of information for me to check out on the engine.

The factory gauge will rise to about half way and then start to move toward the 3/4 point between normal and the hot side. I never have had the gauge go to the extreme hot point but I usually stop the car and let it cool or slowly add fluid when I am able to do so. I know that you have to slowly add fluid to a running engine to keep it from having an adverse effect on the motor. I believe the sender is installed on the intake manifold but don't know if it has been replaced. Intake is an aluminum edelbrock.

Block has not been magnafluxed to my knowledge. Good point about the deck being uneven.

Don't know about bolts as I have not torn down the engine. A local auto repair shop took off the intake and heads and replaced head gaskets. They did identify a head gasket leakage and also found a couple of bad lifters. They replace all the lifters before putting the motor together.

I have not removed the thermostat so I have to assume it is a 180.

The timing was checked and set when I first started having the overheating problem. I did not think it helped. I did notice that the idle lope was not as pronounced as it was when I first purchased the car. It may have been set with wrong timing to make it sound like it had a more aggressive cam. I believe that it has a stock cam rather than an aftermarket.

Since I did not see the heads when they were pulled, I have to assume that they have not been fitted with hardened valve seats. I use a lead substitute with every fill up and use 93 octane or higher. Good point to check if I have to remove the heads again.

Pressure test did not show any problems. I have replaced the radiator cap with a new 16 lb cap just within the last six months but it could be the cap.

I do have a temperature laser gun that I have not used to look for hot spots. I have just checked the radiator and the hoses. I will check all the area that you have suggested.

Lots for me to do. Thank you for your comments.


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## pjw1967 (Mar 10, 2014)

Amen to the timing check. I struggled with running hot for a long time until I set the initial timing back from 6 TDC to 9. The faster I drove the hotter the engine would get. I bought a temp gauge and mounted it under the dash. On a hot Houston day I will run 210-215 out on the highway and 200-205 on regular streets. Since you have the temp gun, try this. Take a cold reading and the start the car. Take readings say every 3 to 4 mins. Be careful to take the reading at the exact same spot and distance. In theory an idling car should run hotter with no air being pushed thru the radiator. Note the position of the factory needle when it gets to its highest point while idling. Then go for a ride and see what the needle does. If it gets a lot higher, then look at your timing. When you're done, park the car, shut it off and then get a reading. Also look to see at that point if fluid is coming out the overflow tube. Report back to us in the bleachers.....


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## djoslin (Jul 30, 2012)

Thanks for the information. I will need to purchase a "good" timing light as the one I have is an old one from the 80's. 

I will make the readings.


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## LouCabra (Jul 20, 2015)

I really don't mean to hijack this thread, but pjw, you said that you installed a temperature gage under your dash. Would that be one of the gage clusters that include temp, oil pressure, and volts? I have been looking for some instructions/advice on how to do that installation, but have come up short. If you have done this, could you post how it was done (e.g. where/how did you come through the firewall, where mounted, how difficult, pitfalls to watch out for, etc.). Thanks, and please excuse the hijack.


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## pjw1967 (Mar 10, 2014)

Hi, Lou. I just did the temp gauge. It's a bit amateurish in that it is just hanging under the dash via a wire tie. Gimme a bit and I'll post some photos of the sender and where it goes thru the firewall.


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## pjw1967 (Mar 10, 2014)

LouCabra said:


> I really don't mean to hijack this thread, but pjw, you said that you installed a temperature gage under your dash. Would that be one of the gage clusters that include temp, oil pressure, and volts? I have been looking for some instructions/advice on how to do that installation, but have come up short. If you have done this, could you post how it was done (e.g. where/how did you come through the firewall, where mounted, how difficult, pitfalls to watch out for, etc.). Thanks, and please excuse the hijack.


Here is a link to the photos I just took. To the purest of the purists, pls keep the flames to a minimum. It was a long time ago, but I think I decided to hack the hole you see in the firewall. The sending unit line is fairly rigid. It goes thru the firewall below the throttle cable, turns towards the pass side behind the vent and then turns towards the rear up to the meter hanging under the dash. There is also a white wire for illumination which runs over to the fuse box. I put a cover over the 2 wires so that the white one can't really be seen. GTO Temp Gauge by pjw1967 | Photobucket


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## geeteeohguy (Feb 2, 2008)

:eek2:


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## LouCabra (Jul 20, 2015)

Thanks PJ. Over the years I have seen so many gauge clusters mounted under the dash boards that I thought there surely must be a lot of information on installing, but nope. Just getting back into the car world again. If I'm able to do a good looking (and working!) installation, I'll fully document it here.:thumbsup:


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