7Westfield Posted January 22 Share Posted January 22 I'd be a bit worried about that thermostat housing. I've had a pressed in fitting blow out of a xflow fuel pump , and this is running more than double the pressure. If there's enough meat there, I'd tap it for a threaded fitting. FWIW SCCA hasn't allowed those fuel fittings for years 1 Link to comment Share on other sites More sharing options...
IamScotticus Posted January 22 Share Posted January 22 (edited) On 1/22/2024 at 3:03 PM, 7Westfield said: If there's enough meat there, I'd tap it for a threaded fitting. That's an excellent suggestion. And a good excuse to put an elbow on. Edited February 20 by IamScotticus Link to comment Share on other sites More sharing options...
IamScotticus Posted February 20 Share Posted February 20 (edited) I made progress, finally, sort of. I got the the three caps, 1, Renault/Dacia Duster (aftermarket) 2, Multiple application Motorad T35 (aftermarket) 3, G2 Mini Cooper (aftermarket) I found the Duster was the expected 20psi; the T35 holding 13psi, regulating at 16psi; then sadly, the Mini Cooper 20psi. The Mini was supposed to be 16psi and would have been the better cap to use. I might have gotten the wrong one. They all fit and all work without leaking. I need to try to find that Mini 16psi cap. Until then the T35 will work, it would be necessary to check it periodically for tightness. Next thing I'm doing is find an auto parts store that rents out pressure testing sets, to try the fit of the adapters to identify this European Renault standard, which OEMs use it, and broaden my search for a 16psi cap that is available domestically. Having said all this, 20psi is acceptable even better, if the connections you have can contain the pressure. With the use of worm gear clamps it should. For me, I perfer to use spring clamps so I'm going to opt for the lower pressure. Edited February 20 by IamScotticus 1 Link to comment Share on other sites More sharing options...
pethier Posted March 17 Share Posted March 17 I procured a coolant cap with the correct seals. Still didn't seem to work correctly. The overflow hose was opaque, so I could not see what was going on. I suspected that this hose might have an air-leak. I junked this hose and put in transparent tubing. Filled the engine to the top of the thermostat housing. Installed the pressure cap. Removed the overflow bottle and washed it thoroughly. Reinstalled and filled it with fresh coolant to the top of the blue vinyl tape. (I have no idea who installed this tape. I assume that it is meant to show a proper "cold" level.) Started the car and ran it until warm. This car has a heater, so I made sure the heater valve was open. Coolant began to trickle into the overflow hose, never filling the hose, but trickling into the overflow bottle. Radiator and heater hose were all hot. Switched off and went away for a half hour. Came back to find that the coolant had come up into the tube several inches. Went away overnight. Came back in the morning and of course the car was all shop-temperature of about 60 degrees F. Overflow tube was full of coolant save for a small air bubble at the top of tube where it connects at the pressure cap. Seems to have taken care of it. Link to comment Share on other sites More sharing options...
MV8 Posted March 20 Share Posted March 20 I'm confused. You mention levels of an overflow hose, overflow bottle, and overflow tube. The hose should stay full, and the bottle should always have enough to cover the end of the hose and never be completely full. Link to comment Share on other sites More sharing options...
pethier Posted March 21 Share Posted March 21 11 hours ago, MV8 said: I'm confused. You mention levels of an overflow hose, overflow bottle, and overflow tube. The hose should stay full, and the bottle should always have enough to cover the end of the hose and never be completely full. That's pretty-much correct. Sorry about using "overflow tube" and "overflow hose" interchangeably. 1 Link to comment Share on other sites More sharing options...
wdb Posted March 21 Share Posted March 21 17 hours ago, MV8 said: I'm confused. You mention levels of an overflow hose, overflow bottle, and overflow tube. The hose should stay full, and the bottle should always have enough to cover the end of the hose and never be completely full. That sounds like an expansion tank that's not under pressure. Link to comment Share on other sites More sharing options...
MV8 Posted March 21 Share Posted March 21 Location of the pressure cap and if the tank is vented determines if it is an "expansion" or "overflow" tank. An expansion tank could be completely filled, adding some volume to the system (requiring an overflow to be added to prevent coolant loss with each cycle) but it would no longer function as an expansion tank, which compresses air filling the space above the cold coolant in the tank. An overflow tank is just an open cup with a hose in the bottom to siphon if the end is kept submerged. Link to comment Share on other sites More sharing options...
pethier Posted March 21 Share Posted March 21 The linear layout on my car is Engine/radiator/heater Pressure cap Overflow tube or hose (transparent so I can tell what is going on). This tube is placed so it will stay at the bottom of the overflow bottle. Overflow bottle with a "cold-level" tape marking about a third of the way up from the bottom. The cap of this bottle is vented to atmosphere. The engine/radiator/heater needs to be leak-free to maintain the column of coolant in the tube. Every time I remove the pressure cap, the tube will empty again. Link to comment Share on other sites More sharing options...
pethier Posted March 21 Share Posted March 21 2 hours ago, wdb said: That sounds like an expansion tank that's not under pressure. That is correct. I call it an overflow bottle. Since the radiator cap is double-sealed, when the car sits and cools down, atmospheric pressure sends coolant up the overflow tube from the overflow bottle to fill the space in the engine system as the coolant contracts. Link to comment Share on other sites More sharing options...
pethier Posted March 24 Share Posted March 24 On 1/22/2024 at 3:03 PM, 7Westfield said: I'd be a bit worried about that thermostat housing. I've had a pressed in fitting blow out of a xflow fuel pump , and this is running more than double the pressure. If there's enough meat there, I'd tap it for a threaded fitting. FWIW SCCA hasn't allowed those fuel fittings for years Back in the day, a fitting blew out of a carb on my SAAB 96 on the grid at BIR. Caused a fuel fire. Link to comment Share on other sites More sharing options...
IamScotticus Posted March 25 Share Posted March 25 (edited) Appears @pethier has a standard open vented recovery tank system on a Kent based engine. The Crossflow, Pre-Crossflow, Lotus TC, BDR/A & Vegan Tune (VTA) were all Kent blocks and the last open recovery bottle and radiator cap cooling systems in Caterhams. All later engines had closed expansion tank systems. Other 7 builders like Birkin and Westfield would fit closed systems to Kent engines, like the Birkin pictured above. An open recovery tank can have a bottom exiting hose to eliminate a situation where a drain hose might pull out and suck air. That would be an improvement to an open system. One of the advantages of the open system is the recovery tank can be placed at any level and still work. This works well in a 7 as most chassis mounting locations are lower than the head. A closed expansion tank should be level with or higher than the highest coolant level. But in a well purged system, I think it could work a little lower. Edited March 25 by IamScotticus Link to comment Share on other sites More sharing options...
pethier Posted March 27 Share Posted March 27 On 3/25/2024 at 1:04 AM, IamScotticus said: Appears @pethier has a standard open vented recovery tank system on a Kent based engine. The Crossflow, Pre-Crossflow, Lotus TC, BDR/A & Vegan Tune (VTA) were all Kent blocks and the last open recovery bottle and radiator cap cooling systems in Caterhams. All later engines had closed expansion tank systems. Other 7 builders like Birkin and Westfield would fit closed systems to Kent engines, like the Birkin pictured above. An open recovery tank can have a bottom exiting hose to eliminate a situation where a drain hose might pull out and suck air. That would be an improvement to an open system. One of the advantages of the open system is the recovery tank can be placed at any level and still work. This works well in a 7 as most chassis mounting locations are lower than the head. A closed expansion tank should be level with or higher than the highest coolant level. But in a well purged system, I think it could work a little lower. A standard open vented recovery tank system on a Kent based engine is indeed what I have. And now, it has a double-seal pressure cap, unlike what was on it when I bought it, so it actually operates correctly. No need to worry about a bottom hose fitting on my car. A properly-placed cable tie around the radiator hose and the overflow hose makes it pretty-much impossible for the hose to pull out. The Triumph Stag had a closed expansion tank well-below the top of the radiator. If you removed the solid cap on the radiator and the pressure cap on the expansion tank at the same time, bad things happened. You would then need to raise the front of the car to go about filing the system without air in it. A company in the UK has a retrofit kit with a metal tank mounted high. I got a little road time in the non-winter weather we had last week, but now we have cold, snow and salt. Link to comment Share on other sites More sharing options...
IamScotticus Posted March 28 Share Posted March 28 @pethier Did you happen to save the radiator cap box, or know the part number? This is valuable information for the owners of Caterham Crossflows with the "special" alloy filler riser. Especially since the cap that fits perfectly isn't known to any OEM to any vehicles in the USA (probably is but..). The cap that was on mine when I got it, and I believe to be the correct part is Motorcraft 1613292. Credit for the pics: https://shop.ford.co.uk/products/ford-motorcraft-radiator-cap-plug I believe this to be a Mk1 Escort item. Not the housing, just the cap, which is interesting in that it is very deep compared to most caps. The problem some have had is they will find a cap that fits the neck diameter, but the depth, although close, won't be sufficient to seal on the bottom. They will have coolant blowing out into the recovery tank and not pressurize the system. I find it interesting that the current "special" thermostat housing offered at Burton had the coolant hose barb reduced to 1-1/4" when the Kent standard hose size had been 1-3/8" for decades. Link to comment Share on other sites More sharing options...
pethier Posted March 30 Share Posted March 30 On 3/27/2024 at 10:37 PM, IamScotticus said: @pethier Did you happen to save the radiator cap box, or know the part number? This is valuable information for the owners of Caterham Crossflows with the "special" alloy filler riser. Especially since the cap that fits perfectly isn't known to any OEM to any vehicles in the USA (probably is but..). The cap that was on mine when I got it, and I believe to be the correct part is Motorcraft 1613292. Credit for the pics: https://shop.ford.co.uk/products/ford-motorcraft-radiator-cap-plug I believe this to be a Mk1 Escort item. Not the housing, just the cap, which is interesting in that it is very deep compared to most caps. The problem some have had is they will find a cap that fits the neck diameter, but the depth, although close, won't be sufficient to seal on the bottom. They will have coolant blowing out into the recovery tank and not pressurize the system. I find it interesting that the current "special" thermostat housing offered at Burton had the coolant hose barb reduced to 1-1/4" when the Kent standard hose size had been 1-3/8" for decades. I have that stuff in my shop. I will try to remember to get it for you. 1 Link to comment Share on other sites More sharing options...
pethier Posted March 31 Share Posted March 31 1 Link to comment Share on other sites More sharing options...
Mudder Posted May 3 Share Posted May 3 A BIG THANK YOU TO "IamScotticus" His Cooling System analysis and recommendations are spot on. I followed his advice in every detail and can report that the sealed system works perfectly. After 5 road tests totaling nearly 800 miles of occasionally very spirited driving, and everything from stop and go traffic in cities to climbing 11500ft passes in the Rockies, my new sealed system has not lost a drop of coolant. The temp. gauge stayed right around 80C the entire time. The warmup is nice and expeditious and everything works as advertised. The system utilizes an Elise expansion tank, mounted on top of the cruciform behind the radiator and a "submarine" which tees into the bottom radiator line. My 1700 Xflow S3 has a heater. No issues, whatsoever. GREAT JOB, SIR!! 2 1 Link to comment Share on other sites More sharing options...
pethier Posted May 13 Share Posted May 13 On 3/31/2024 at 12:08 AM, pethier said: Got the autocross tires on the Prisoner wheels on Friday. Car started right up after its winter nap. Put the car in the trailer and headed for Eau Claire. Saturday morning early, arrived at Rock Falls Dragstrip. Autocross in the parking lot. Finished 17th of 48. This is certainly the first USA-style autocross this car has done. Sunday I returned home and took my neighbor for a good long ride. Then we hopped in the Cayman for a totally-different sports-car experience. Cooling system worked fine throughout. I'm still having a problem remembering to switch off the turn signals, even though they show atop the fenders. I may need a loud beeper. Getting used to left-handed shifting. Under autocross conditions, I'm not ready for prime time. 2 Link to comment Share on other sites More sharing options...
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