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To ascertain the location of my coolant leak, Bill Carlquist advised me to remove the valve cover, the intake and exhaust manifolds, the tappet covers and the oil pan, then pressurize the system to 20 psi and study everything to find the leak. It then took me about a week to find a cooling system pressure tester that would work on the MGA radiator. I borrowed a tool from Autozone with about 15 attachments, and then had to borrow a supplemental pack of maybe 6 additional attachments before I found something that would work.
Before starting, I removed the oil filler cap, and it was covered in the mayonnaise that we saw at the track. I then removed the valve cover, but the underside appeared to be clean. So I thought that maybe I didn’t have a leak after all, and what we saw on the radiator cap after my run on Saturday was just from some residual water in the system.
So I run the engine a few times, warmed up, to about 2,500 rpm and let it run for a bit – say 10-15 minutes each time. The engine seems to have a slight skip and when I pull the plugs, the #3 plug is moderately wet, but it doesn’t smell like gasoline. Could be oil; could be water. I verify that the plug is firing when held against the side of the engine, and I even use the Colortone device to verify that the plug will fire in the combustion chamber (it also comes out “wet”). The ignition on all of the plugs, however, shows “rich” with the Colortone, even when I adjust the carburetors to maximum lean.
I play with the carburetors. For the race weekend, I had set the carburetors as follows: Front - .082” plus one flat; Rear - .082” plus three flats. When measured at the track due to questionable performance, the carbs measured as follows: Front - .082”; Rear - .102”. The spark plugs looked like the carbs were running rich, so I adjusted them to Front - .050” and Rear - .052”, running #7 needles. Back in the garage, however, the carbs measured: Front - .068”; Rear - .088.5”. I reset both carbs to .068” even though they both seem to run just slightly lean at .082” at idle. I’m thinking of abandoning these carbs and going back to my H-6 carbs.
After running the engine as described, there did seem to be condensation under the oil fill cap, although not the mayonnaise. That symptom, together with the #3 plug being “wet” caused me to proceed with the cooling system pressure test.
Initially, I was afraid to pressurize the system to 20 psi, so I pressurized it to 15 psi. Because of the amount of work involved, I only removed the spark plugs and the valve cover. I could not see any evidence of a leak. The system held pressure for a long time, but the next morning, the pressure was down to about 7 psi and I saw evidence of two leaks under the car. One seemed to be under the radiator, driver’s side, while the second seemed to be under the back passenger side corner of the engine.
I spoke to Bill Carlquist and he told me not to be afraid about over pressuring the engine. So for the next test, I removed the carburetors, intake and exhaust manifolds and tappet covers. I still had no ambition to crawl under the car to remove the oil pan.
This time, I pressurized he system to about 21.5 psi. I noticed that my lower radiator hose was leaking, so I tightened the fittings. That would explain and eliminate one of the two leaks I had seen earlier. Over the course of about 4.5 hours, the system lost about 2.5 pounds of pressure and I noticed two leaks under the car – one under the right front of the engine, the second under the right rear of the engine – both estimated at about a teaspoon worth of fluid. I could see a leak at the thermostat gasket, so I tightened down the three nuts holding the thermostat, seemingly eliminating that leak. The second leak seemed to be coming from the head gasket at the right rear of the engine. The next morning (about 5 hours later), the system was holding 17 psi, and the spots on the floor underneath both leaks had essentially dried up.
So now I’m assuming that I have a head gasket leak or perhaps a cracked head near the right rear of the engine (passenger side). To more precisely identify the location of the leak, I coat that area of the engine with baby powder, the theory being that the baby powder would show a track leading back to the location of the leak. This time I pump it up to 27 psi. Within half an hour the pressure drops to 26 psi and I see weeping at the top of one of the thermostat studs and the top of several of the studs holding the head. I see nothing at the rear corner of the engine. My baby powder is dry. I can’t do much with the thermostat studs, but I dry all the studs and put a paper towel on the thermostat. Pressure goes down to 25.5 psi after another 11/2 hours, but I don’t see any leak other than at the thermostat stud. Three and a half hours later, pressure continues to hold at about 25 psi. I’m thinking that the leak noticed at the right rear of the engine was really water migrating along the flange for the valve cover from the thermostat.
My tentative conclusion is that I do not have a cracked head or block or a head gasket failure. I'm starting to reassemble the engine.
Thanks Jeff. Brakes have been gravity bled and the wheels swapped out. Hoping for at least a single dry session but won’t be offended if it rains all day too
I really needed this day out on track. Left home at 4:45 and after one stop to get coffee and another to get gas, I made it to Thompson a little after 7 AM. Given that this is an SCCA sanctioned Time Trial event and my region, MoHud is running with CART, some of us had additional roles. I went and set up grid using cones with numbers on and then set up cones for pit in and pit exit lanes. Emptied my car out and then completed tech.
But with all the activity in the AM I barely had time to adjust the car. First session I went out driving the car as I had driven it in. To ease up the groups, they put me in an intermediate group and there was a lady in a Mazda 3 that clearly did not belong who was very timid with her point bys added to which she was pointing by in the corners. Came in with a dry lap time of 1:34 which wasn't too bad for my first session driving on track this season. Then the rain started. It was fun at first because I clearly had an advantage with the FWD over the others. But as the rain got worse, the rivers started flowing down the front straight and there was nothing I could do. There were multiple rivers too nearing the kink and past it into the braking zone. I could see my top speed dropping from triple digits to high 90s as the day progressed. The front axle would hit a river, and then the engine revs would climb but the car would move either left or right and then take off only to get caught in the next one. Braking was good offline into T1 but very sketchy staying on line. One of the Corvette drivers in my group pirouetted around twice as he caught water at the brake zone and was lucky not to hit anything. He packed up right after and headed home. I stayed until the Time Trial was done which happened during the worst of the rain. Came second by about 7 seconds to the Toyobaru in first - possibly better driver on better tires too. After the TT, I packed up, stayed for the trophy ceremony and headed home. With a smile on my face even though the drive home was sketchier than on track with all the water and hydroplaning galore.
As this season dawned, I've had thoughts of throwing in the towel. I am a father now and I see people dropping off. Greg is out and Jeff has been talking about retiring the S2000 which means we may never run on track together. Added to that Steve (Quantum) has closed and whoever else is out there is not stellar or have been assholes. The car is not at its best and I have to nurse it through the season. But going out there on track and running laps in less than ideal conditions with intermediate traffic was worth it. A few years ago I would have been livid and angry being held up. But I was calmer and relaxed. I enjoyed it and came back in.
Some people golf, and I have tried it too. I was terrible at it. The other sports I was marginal at and my favorite Cricket is not something that is as widely played here. To me going out on track and doing those laps is so peaceful that I think this is my golf. I need this in my life as a welcome break and release from when the main aspects of life get tough. So I will soldier on, and if I have to sell the cars I own and get something else. That is what I was thinking on my way back home yesterday.
Over the past few years I have spent an inordinate amount of time working on the MGA - all without any significant results at the track. My lap times are pitiful! The pinnacle of my career seems to have been in October, 2021. Since then, I've gone backwards!
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I've spent the last month chasing an internal coolant leak - and I don't think I found it. I will be scrambling today to finish up the prep and get the car on the trailer and to the track by 5:00. Time will tell how tomorrow goes.
So tomorrow and Saturday is the Empire Cup at Lime Rock. This has grown to a significant event, and I believe all run groups are full. My group has 35 cars listed! That is a huge grid! My first run tomorrow is at 10:40 My first run Saturday is at 9:00. I'm looking forward to an exciting and fun weekend.
Weather may be mixed with thunderstorms on Friday and some rain on Saturday. But I hope you have fun. I’ll see if I can swing by with Antara in tow and will call Saturday to confirm.
she wants to go to Champlain to see if she can spot Champ, so I’ll have to act at my persuasive best.
Great day at Lime Rock yesterday. Got to spend some time with Jeff and see one of his races. He did well and completed a few passes. Antara joined me and we held up a sign for Jeff to cheer him on.
05-17-2023, 08:10 PM
