Good news Henry and so glad the heads are ok. I managed to catch my 7 on it's way to overheating due to the shaft/impellor loosening on the water pump. I checked compression and all was well. I know what you mean about the rain, I hate being in my garage when it is raining, working on the 7. Still we have plenty to look forward to. I'm off to Bicester this weekend and the TR7 is to be placed in a prime position :) for the Classic weekend!! Might raise a few eyebrows amongst the Ferraris & Alphas, plus I'll be driving it all the way there & back too!
My Stag temp gauge only gets about a quarter of the way up too. I replaced the temp sender and no change whatever so I think its just the way some of them are, as I think the thermostat operates fine. I've also noticed sometimes the steam from the exhaust can take a seeming age to clear from cold, maybe as much as 10 mins idling in winter. Also 20-25 PSI would seem fine for a hot engine after a decent run, so I hope you find this to be some re-assurance that these things are all OK!! The rad could be a different matter though, hope the radweld works for you!
I do Laurel, thank you. All very reassuring. Although I am thinking about just checking the torques on the heads. My dad seems to think running hot could have loosened them and although I don't understand why, not checking would be even more stupid then letting the coolant fall so low in the first place!
Hi Henry, great that your head gaskets are ok but I would certainly budget for a new radiator as that rad weld will itself block the fine coolant galleries causing future overheating. The mk2 Stag certainly does have cylinder block drains, but whereas the mk1 had a wing nut type drain the mk2 has a plain bolt, one either side that can be undone to drain and flush the block. Keep up the good work 👍
Although it probably isn't head gasket, I'd be concerned by the sudden drop in oil pressure though mine only idles at about 20 - 25psi when warm but goes back up to 40-45 when at driving speed
Take the plugs out and check them. If there is water getting in to a cylinder - which would cause the steam from the exhaust - then the plug will look cleaner than the rest. Also the sniff test needs to be in a bung for the pressure to build and force gas thro the liquid. I’d say u did it long enough to get a result but works better with a bung. Good luck
Thanks, I did wonder if the sniff test needed to bung to allow gas build up so following your note I’ve just been out and retested it. I couldn’t stick the bung in so I pressed and held it firm against the hole. Pressure clearly built up because I had some bubbles and the coolant started coming up the pipe. No colour change so I’m happy still.
I don’t think you are getting a gas tight connection with the engine using your method with the funnel. You need to put the bung back where you are putting the test and take the cap off the expansion tank and put the rubber bung with the tester into the expansion tank neck and then do the test again. Good luck.
I had a similar problem, it would dump it's water , topped up ok drive around few days , and dumped water , topped up ok , what it was perforated rad core ,when it driven the debris would fill the hole until it gives way under pressure repeating the process , new core fixed it for good , I agree not gaskets ,
Good job, The engine sounds fine and it the head gasket had gone the compression would have bin down and uneven running etc...Lucky break. all the best Bob
Given you had visibly lost coolant when you had to be recovered, I think head gasket failure is unlikely. Feels more like an air lock leading to localised overheating and subsequent over pressuring of some weaker point in the system. That said, the sniff test kit requires the air from the system to bubble through the liquid though to work, so you do need the rubber bung to make a seal. You’d want to fit that to the expansion bottle as that’s where your rad cap is. They work by changing colour if carbon dioxide or partial combustion product gasses are getting in to your cooling system, and to detect this those gasses need to bubble through the test liquid. The rain has been a pain I know! You’ll get there with the TR7 though :)
A timely one Henry as I overheated my TR7 convertible before the winter. When I checked the oil filler cap it was covered in the dreaded mayonnaise so I haven’t dared drive it since and am resigned to having to replace the head gasket. I wonder if I’ve made a hasty diagnosis and should get one of those testing kits? As a footnote, back in the day I overheated my Vitesse numerous times and never had a head gasket issue - the old cast iron engines must be much more tolerant to getting too hot!
maybe check the water pump if no leak visable and do ya test on the expantion tank in air at 2000rpm it s a good way to know so ya don t damage engine ,oilpressure got hot angled head bolts mayybe all connected happy days sorry if its a bit neg but am a reallist
17:30 I would have thought that temp is sitting very low. Normally mid position? You could have a sticky thermostat. Knowing the coolant issues with these engines I don't think I'd be using Radweld.
It has always (last 20 years) run with the temp position showing low. I figure it is the change that is more important. If I know it runs around there then when it is higher I know there is an issue. As for the Radweld, I'm afraid I've already done it
Them stags all ways used to over heat bad you need to get a bigger or better radiator or put electric fans on i used to know a friends dad had one and it used to do it mate so i would sort it out before the head gasket gos and the body's used to rot bad as well as i had to do some welding on the sills good luck mate
Thanks Peter, this car has been in the family since the 1980s without an overheating problem. As long as you keep the coolant mixture right, with a regular flush, so the channels do not get blocked up you should be good.
I owned an identical red Stag back in the 80's and that thumbnail of your Stag with the bonnet open by the roadside is so familiar to me. Do what I did and just get rid of it.
