O No!!! Killed my '70 srl?

[less frustrated]

It was a hot day recently in Delaware. I decided to take the roadster about 50 miles and then return. Ran great until almost home when the engine temp pegged at hot, hot, hot. Pulled in the driveway and popped the hood. Fan belt had broken. Put the car in the garage and there it sits. Advice so far is to pressure test the cooling system to see if the head gasket may have blown. Would anyone share a list of things a non-mechanic could check to decide if I need to take it to a 'specialist'? Any suggestions for a cooling system pressure tester for these cars that doesn't cost an arm and a leg? I am 73 and retired so anything I spend doesn't get replaced. I don't like being this bummed out.

[FergO2k]

Others who are more knowledgeable will weigh in, but you may have got lucky.
So if head gasket blows, then you have a new passage from a water jacket thru to oil, or water jacket thru to cylinder. The second usually results in white smoke as the engine makes steam, and the water getting into cylinder can make things run rough depending on amount.

Water into oil jacket is easier to check, as either (or both) dipstick and radiator cap are going to show evidence of brown sludge ("root beer") on them.
Make sure engine didn't lock up / seize when it cooled down. This is done by putting large socket/breaker bar on crank and making sure everything turns freely.
Looking at plugs to see if one looks way different than others can be an indicator of where the breach happened, if it did. But reading plugs takes more of an expert eye than mine.

[david premo]

Sorry to hear about that, you will need to do a lot of evaluation if it overheated as bad as you say. It could be much more than just a head gasket. Before tearing down the engine run tests including a compression test, and start the engine if there is no water in the oil after you fix the cooling system problem. Also replace the thermostat before you run the engine as it’s likely bad at this point from excessive heat. You will want to check that there is no combustion gases in the cooling system because that is one of the ways head gaskets can fail is into the cooling system. Good luck with it, I know that there are a few members here that have rebuilt their engines in nearby places to you. You might want to find out what machines shops in your area that have rebuilt U-20 engines.
Dave

[drieseck]

L. Frustrated,
If you drove back to your driveway it could also be less drastic than a rebuild. Did it die, or you turn it off? Was there white steam---everywhere?
Just IMO, before a specialist: look for contaminated fluids (oil dipstick & coolant rad) "root-beer" looking stuff --as Fergus instructs. If so, go to Dave's post. If not: try removing coil wire and turn over motor (one quick rotation, see if it is frozen-up, not numerous times or you can damage), or (per Fergus), put a socket and turn manually. If it isn't frozen, w/no contaminated fluids): a new belt, new thermo (per Dave), new coolant, plugs. Before you tighten the belt, check water pump - is it frozen or dripping out the weep hole? If frozen, replace with rebuilt: (http://www.waterpumps.bizhosting.com/index.html) or new-from-vendor. These are fairly stout and can take some punishment before major damage. Post your findings, there are smarter guys------- here that will walk you through tests and checks, usually better than most specialists.

[redroadster]

Ideally it should blow the pressure ( fluid steam ) out the cap ,and you'd see that before big damage occurs
esp. on lite vehicles like a 311 , you need to pull off the road and let it cool down , the acess the situation ,is /was it full of coolant a fill tank funnel recommended

[Gregs672000]

All good info and suggestions. But yes, let's slow down... it may not have gotten super hot for very long and we don't know if it did damage or not. As stated, check the oil and coolant, pull the plugs and examine (note any significant color difference, white or very clean would suggest it saw coolant), rotate the engine, preferably by hand (and much easier with the plugs out)... there will be some variation in how easily it rotates as you turn it but that's normal... obviously if it's seized it will not turn! If all seems good, I'd get a new belt and 180 thermostat and fire it up. If I were you, I'd want to know NOW, and the thermostat housing requires a specialized gasket to work right and probably not available locally (vendor item). However, you can make one (two actually) using gasket material for gaskets exposed to water (specify this at the parts store) by carefully tracing the housing, noting how the thermostat fits into the housing and trimming out the little spot at the top of the housing that allows air bubbles to bypass the thermostat. Then you'll need to take several strands of copper wire (stripped from any spare wire you have in the tool box) about an inch long and punch a very small hole in the widest part of the gasket so you can JUST slide the wire in half way and bend it over to replace/act as the metal tab that comes installed in the stock gasket. These metal tabs are required for the temp sensor to ground/work and it won't without it (though I have a work around later if needed). A hole punch tool will make this much easier (rotating head with several different size punches) and is a tool worth having. Don't use any gasket sealer on the gaskets, or if you use just a little be sure the wire/tab is clean in order to make contact with the metal. Or, if you have more patience than I, you can wait to get gaskets in the mail! However, I don't think you need to replace the thermostat before you fire it up to see how it runs etc as it won't be running for long, but Dave is wise to suggest it be replaced regardless to avoid future issues.

So, to summarize, I'd investigate, if ok replace the belt, fire it up, if OK order/make your gaskets, get/replace the thermostat (requires draining some coolant from the radiator, can be hot) and hope that all remains intact in the mighty U20!

I understand and share your budget concerns! I'm hopeful that your quick attention avoided any major issues. We'll take this step by step and hope for the best!

I re-read your post, noting is says you're not a mechanic. However, if you have some basic tools and a sharp pair of scissors, razor blade, hole punch and a socket big enough for the crank bolt (22mm?. Not sure... I'll check) you can do all I said above. Feel free to ask any questions... we're here to help!

[less frustrated]

This community is the best. I shut it down and restarted to pull into the garage. All my tools are 50 miles away. I'll retrieve what I think I'll need and get started, slowly as recommended. I rarely buy aftermarket. Datsunparts.com routinely. Let's see if I can muddle through. And it was running so sweet. And not using the stock temperature gauge. Using a mechanical gauge. Using everyone's advice, my brain is starting to formulate a plan. Thanks to all.

[FergO2k]

If you don't have a large socket to test for if it is seized, you can put it in 2nd gear and VERY gently rock it fwd and back. If it is seized, you won't see movement of the fan. If it is seized, you won't do any more damage than has already been done!
I never considered a thermostat could be overcooked, but that makes total sense. Definitely put close attention on hoses as well, as this is the time to change them if any areas have got real soft.
If it can be started and then warms up REAL fast, it is because exhaust heat is going into the coolant flow, and indicator of head gasket breach, but not a bad thing because then oil (usually) is not contaminated.

[less frustrated]

Removed spark plugs. All medium shade of gray. Had been running 110 octane, leaded gas. Borrowed a cooling system pressure tester. Poor fitting. Added about a quart of commercial 50-50 mix. Pumped up to 20 lbs. Stayed there for a minute or so. Pressure is escaping at the cap for the overflow reservoir. Wouldn't fit on the radiator itself. Pumped back up multiple times. Could see no leaks on or around the engine. Oil looks fine right now. No moisture on cylinders that I could see. Put socket on crank nut. Engines turns freely.

[Gregs672000]

Sounds good to me! Your quick reaction appears to have paid off. I'd run it and plan to swap out the thermostat sooner than later. My engine would LOVE 110 octane!

[Daryl Smith]

If the water pump wasn't turning because of the broken belt, that would likely be the cause of the overheating, and easily fixed with a new belt.
To be on the safe side, I'd check that the water pump and alternator turns over freely, and was not part of the cause of the broken belt, vs just an older fan belt.

[less frustrated]

Thanks. The alternator turns freely. Having trouble finding a belt. I found a listing on Amazon that said it is a fit. We'll see. Should the water pump pully turn freely? I know you said it should. Like freely by hand?

[rwmann]

Where is 110 octane leaded fuel found these days? Local general aviation airport?

[david premo]

Yes your pump should turn easily by hand with very little resistance.
Dave

[Nded]

Where is 110 octane leaded fuel found these days? Local general aviation airport?

We can get 110 here at VIP Racing Fuels near St Petersburg FL.