Austin240Z Posted February 29, 2008 Share Posted February 29, 2008 So here's the situation, for now I have the stock L24 block and E88 head, running dual SU's with the coolant pre-heater hoses hooked up, heater core is also hooked. I have a new radiator, new water pump, new 180 degree thermostat. At an idle the car will overheat in 4-6 minutes. I had not been able to run the car for more than a minute up till 3 days ago(long story), I had drained the radiator and removed it. 3 days ago, i re-installed the radiator and timing cover, and filled the radiator up with coolant. I started the car with the intention of running it up to normal operating temperature for the first time. Immediately checked all my gauges, amp fine, oil pressure a little high but ok, water temp was still pegged at the bottom as expected. At 2 minutes I double checked everywhere for leaks, no problems anywhere. At 3 minutes I double checked the Temp gauge, still pegged at the bottom. The valve cover and head were pretty hot to the touch, but the radiator was still cold. Here's where the trouble starts: At 4 and a half minutes I realized I was in trouble. I was tripple checking for leaks when i noticed smoke puffing out of the block vent(pcv) which i had left open, I also noticed smoke coming from the breather on the valve cover. I checked the Temp gauge again.... still pegged at the bottom... The radiator was still as cold as it was before i started the car, but the Valve cover was very hot, as was the lower radiator hose. At 5 minutes, with no change in the Temp gauge I decided it was a good idea to shut her down, and trouble shoot. As soon as the engine stopped 1 full gallon of coolant came shooting out the overflow hose and all over the ground. Steam started rising from the radiator that was suddenly scalding hot, which 15 seconds prior had been ice cold. I decided it was time to go buy a new gauge and then troubleshoot. I drained the system, hooked up an autometer temp gauge in addition to the factory gauge, flushed the system and then refilled it. I ran the car a second time. Checking both gauges periodically for the first 3 minutes, everything was about the same, both gauges still at the bottom peg. At 4 minutes then engine felt pretty hot to the touch, and though I expected a change in the temperature on the gauge, it hadnt moved. At 6 minutes I started to see the first puffs of smoke out of the block vent. With a lack of temperature readings on both gauges, and an ice cold radiator, I decided it was probably a good idea to shut the car down again and regroup. Important: As soon as the engine stopped, paying more attention this time, I noticed that a heard a noise which appeared to be the thermostat opening and closing wildly for a split second. Then another in another split second close to a gallon's worth of coolant came rushing out of the overflow into my now makeshift overflow tank. I had left some water in the lip around the top of the radiator which quickly started steaming within 10 seconds after the coolant had come rushing out of the overflow. That's about the gist of it. I did not have a chance to run the car a third time. My Thoughts: Based on what I observed, it doesnt seem like coolant is able to circulate to the outlet where the thermostat is while it's under pressure. Since both of my temp gauges are mounted in that area, that definitely seems to be the reason for the lack of a temperature reading. I am not sure what could be causing the problem, The head isn't all that clean(my good head is in shambles thanks to a shitty cam) but there were no visible obstructions and I had run water through it while it was off the car to make sure it came out everywhere it was supposed to. The only thing I can figure is a possible air pocket in the top half of the head in and around the water outlet due to my draining and filling the radiator. I have not had a chance to run the car a third time, so I havent been able to check and see if the air pocket was forced out if that really is the case. This car has a knack for developing ridiculous, complicated and unusual problems and at this point I'm losing the fight when it comes to figuring them all out one after another. Any insight would be greatly appreciated. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted February 29, 2008 Share Posted February 29, 2008 I think you have the thermostat in upside down. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted February 29, 2008 Share Posted February 29, 2008 I had a simaler problem, mine was a plugged radiator. I had it rodded out and all was well. Quote Link to comment Share on other sites More sharing options...
SteelToad Posted February 29, 2008 Share Posted February 29, 2008 I think you have the thermostat in upside down. I've put one in upside down before and it acted just like you describe. The heat builds up on the hot side of the thermostat and slowly migrates to the cool side until the metal is hot enough to force it to open just a crack. Once this happens hot water gets to the sensor side, and the thing pops open allowing all of the built up pressure past in one violent flush. Make sure you flush the whole system, violent discharges like that could suck air bubbles up into your cooling system. Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted February 29, 2008 Author Share Posted February 29, 2008 I've put one in upside down before and it acted just like you describe. The heat builds up on the hot side of the thermostat and slowly migrates to the cool side until the metal is hot enough to force it to open just a crack. Once this happens hot water gets to the sensor side, and the thing pops open allowing all of the built up pressure past in one violent flush. Make sure you flush the whole system, violent discharges like that could suck air bubbles up into your cooling system. The only problem with that theory is that both sensors are on the hot side before the thermostat. The thermostat doesnt open until the car and water pump are both OFF, the thermostat does not open while the car is on. When I Installed the Autometer gauge, it seemed like there wasnt much coolant in the water outlet. Also, it looked like there was only enough room to put the thermostat in one way. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted February 29, 2008 Share Posted February 29, 2008 An easy way to test for a bad or mis-installed thermostat is to remove it. Run the car with the water neck reinstalled (sans thermostat) and see if the problem goes away. Quote Link to comment Share on other sites More sharing options...
Clifton Posted February 29, 2008 Share Posted February 29, 2008 I think you have the thermostat in upside down. This would be my guess too. Is the larger copper part on the bottom? If so I would run it without one and run it again. Quote Link to comment Share on other sites More sharing options...
Mr.INSANE Posted February 29, 2008 Share Posted February 29, 2008 Keep in mind your thermostat could be broken as well if it did not move at all Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted February 29, 2008 Author Share Posted February 29, 2008 OK, I appreciate the suggestions in regards to the thermostat, but again, the thermostat is in correctly. I sell thermostats all day every day, I understand the way they go in, the concept of how they work and even the materials they are made of. I work with mechanics, good ones, I told them of my problem and their first thought was a collapsed hose. I had also checked for that, and it does not apear to be the case either. A few experienced people on another Z forum seem to agree that their may be an Air pocket, and they suggested way to check for it and fix it. Since i had so many posts about the thermostat, I will check it again, and replace it with my second new thermostat(at this point I buy parts in sets of 2) I am curious if anyone has any ideas other than the thermostat? Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted February 29, 2008 Share Posted February 29, 2008 I had a simaler problem, mine was a plugged radiator. I had it rodded out and all was well. I had the exact same symptoms as you, and this was the problem. I suggest you consider cleaning it out and backflushing. Mine was plugged but I could not tell by looking through the radiator cap opening. You should not have air pockets if you burped and bled the air out of the cooling system. Evan Quote Link to comment Share on other sites More sharing options...
Clifton Posted February 29, 2008 Share Posted February 29, 2008 For it to overheat enough to pop the cap in 4 minutes, it sounds like there is zero flow. You could pull the T stat and start the engine and see if fluid runs through. Quote Link to comment Share on other sites More sharing options...
woldson Posted March 1, 2008 Share Posted March 1, 2008 Water pump. I once had a pump where the vains that are pressed on, started to spin freely. Easy test remove thremostat and run it, frist. Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted March 3, 2008 Author Share Posted March 3, 2008 Update I replaced the thermostat with another new 180 degree did my best to eliminate air pockets, no apparent movement of the coolant in the radiator when I was looking in from the top, and still no flow until the engine is OFF. She's still overheating, and fast. Still no reading on EITHER of my two temp gauges. I then removed the thermostat all together. I did have some flow, but it didnt appear to be much, the radiator is now cooling the engine somewhat, but again, it is still overheating quickly, and again, no reading from either of the temp gauges. Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted March 3, 2008 Author Share Posted March 3, 2008 In addition heat feels like it is being dissapated evenly across the entire radiator, no cold spots I could feel. Quote Link to comment Share on other sites More sharing options...
ZeeNoEvil Posted March 3, 2008 Share Posted March 3, 2008 I had to finish up after someone else on a MG restoration and ran into similar symptoms, also with a "new" radiator. A plastic plug was left in the lower outlet. it was painted black and almost impossible to see. Hope this helps. Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted March 3, 2008 Author Share Posted March 3, 2008 I had to finish up after someone else on a MG restoration and ran into similar symptoms, also with a "new" radiator. A plastic plug was left in the lower outlet. it was painted black and almost impossible to see. Hope this helps. haha, hadnt thought about that as a possibility, my radiator didnt come with plugs and I had a single shop towel in either end when it spent a while out of the car, which was removed before the hoses were put on. So unfortunately that's not the case. Thanks for the idea though. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted March 4, 2008 Share Posted March 4, 2008 I've heard of water pump blades eroding away, or the cheapo sheet metal ones breaking. Maybe your water pump isn't pumping at all? Mario Quote Link to comment Share on other sites More sharing options...
woldson Posted March 4, 2008 Share Posted March 4, 2008 If the engine really is getting that hot, with no thrmostat and no read on the gagues.... If the engine was really getting that hot then natually you would read something on the gauges. I mean its not like they need to be in water to read heat. So let say that the engine is at 230 after shut off the temp gauge would start to read mabey up to 150ish due heat at the mount. Get one of those inline flush kits and hook up the hose to it. Water should be shooting out of radiator and keep the engine cool if you dont have a blockage. Then look at the water pump for the problem. Cooling systems seem to be so syimple yet have caused me great heartache. (note my frist post, haunted me for at least a year) Quote Link to comment Share on other sites More sharing options...
chrism Posted March 4, 2008 Share Posted March 4, 2008 At the risk of sounding stupid. You got a belt on the water pump? I've made some stupid mistakes and that would be one of mine. Quote Link to comment Share on other sites More sharing options...
Austin240Z Posted March 4, 2008 Author Share Posted March 4, 2008 I've heard of water pump blades eroding away, or the cheapo sheet metal ones breaking. Maybe your water pump isn't pumping at all? Mario That's one posibility I am considering, it is a brand new water pump, but I have seen them bad off the shelf, so I'm going to have to eliminate that too at this point. If the engine really is getting that hot' date=' with no thrmostat and no read on the gagues....If the engine was really getting that hot then natually you would read something on the gauges. I mean its not like they need to be in water to read heat. So let say that the engine is at 230 after shut off the temp gauge would start to read mabey up to 150ish due heat at the mount. Get one of those inline flush kits and hook up the hose to it. Water should be shooting out of radiator and keep the engine cool if you dont have a blockage. Then look at the water pump for the problem. Cooling systems seem to be so syimple yet have caused me great heartache. (note my frist post, haunted me for at least a year)[/quote'] Well, i figured out my gauge problem, The stock gauge is not working. THe autometer gauge is in a bad place and that is why it is not working. I am going to re-mount the autometer in a better location tomorrow. After I ran the car for 4 minutes and then let it sit for 4 minutes i hooked the wire up to the stock sending unit just to see if it would read. I got a reading of 210 degrees. I am not sure if there is a difference in the way the Stock sending unit and the autometer sending unit read, but that was a big surprise. I should have an accurate temp reading tomorrow. I have already used an inline flush kit and I was seeing fluid shooting out of the radiator. BUT the thermostat was still in at the time, so I will probably do it again tomorrow. At the risk of sounding stupid. You got a belt on the water pump?I've made some stupid mistakes and that would be one of mine. I do have a belt, haha, that was the first thing I checked. Quote Link to comment Share on other sites More sharing options...
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