Bleedin' radiator! HELP/discuss pls......

[ROD]

More testing......added more antifreeze to give 50/50 mix,and also 7lb long neck cap.Rode the test run.Temp marginally better,but hardly noticeable.Still hitting 100 degrees after about 10 miles or so at 50 ish mph.If I kept running at that speed it would spit for sure.Rad has difference of about 10 degrees top to bottom after the run.  
  So thats it for a while,as going away for a few days to recuperate my aching brain!
 Im going to try another 8" bike fan on the front of the rad,up tight to the fins,so that I have one pushing and the existing one pulling.I will also try a 13 lb long neck cap.I just cant think of anything else to try TBH!
 
 If it is overheating at constant 50 mph,surely that means that the rad isnt getting rid of the heat? After about 5 mins or so of much slower (30/35 mph) running immediately after the 50 mph run ,the temp drops by about 5 to 10 degrees.To me ,that means it can cope with cooling at the slower speed ,but not the higher?

[kapri]

Have you checked the voltage yet Rod ? I thought I had a problem on the POS with what looked to be high speed overheating  and it turned out to be overcharging . I even went so far as to send the brand new gauge and sender back to the manufacturer as I was convinced it was that at fault .

[morrag]

Rod, here's a thought! you haven't got a problem with the motor have you? cracked block , combustion chamber to water gallery perhaps? because I would have thought you have covered all avenues on the coolant side by now!! So maybe worth a gander.........Morrag

[morrag]

As a further thought!! engines years ago were cooled by thermo-syphon, and did not therefore have the benefit of a water pump, let alone an electric fan! and still managed to run at an acceptable temp. Indeed they normally didn't have thermostats either, or heaters to confuse the issue, and that's Ford 8 & 10's, Austin 7's, and a host of others, often still in production in the 50's. True they were cast iron motors, but the alluminiuum construction of the Reliant should be a bonus!......hey, ho......Morrag

[terry t]

Theres one other thing the fan may be to close to the rad 
Looking at the photos it looks as if not doing any cooling to the engine. cant you refit the original reliant fan onto the water pump

[digger06]

its getting too complicated imo,
my set up is standard from a reliant except for no water to the manifold etc, its bypassed.
and its got a leccy fan,very very close to the rad,(bike one) running off a thermo switch, more water than coolant at the mo..

runs perfect, fan comes on in warm weather in traffic, never on the longer rural roads,
so why is yours doing this when its very similar to mine?
had a few with your symptoms , and im with morrag, its ALWAYS been down to cracked blocks, head gaskets, bad heads, restricted passageways

the only thing i would say is, like others, i think the rads mounted a bit low,
,

[digger06]

Bleedin' radiator! HELP/discuss pls......

not the best pic, but you can see the rad and fan(fan isnt clear, its tight to the rad, nothing else fancy fitted cept a small catch tank on the rad

[terry t]

Didn't this engine have a full rebuild last year. spent loads of cash on it. had a chunk out off no 1 piston. so new liners pistons and rings plus wasn't there a problem with the crank  . i would do a compression check and a cylinder leak test. try flushing out the water ways

[digger06]

reliant engines have the cyls very near each other, easy to get a leak to/from cyl to/from the waterways via the headgasket,
was it checked for warp?

[spanners]

makes me wonder about the ,grade, /quality, of the cyl liners .

[terry t]

Found this on  RODs Build. Reply on page 608 and 614

http://www.mankymonkeymotors.co.uk/forum/index.php?PHPSESSID=9bd7ae55e8651f83c897a058ff9de2a3&topic=5497.600

Rod did you have standard liners and pistons fitted. i may have a block here so you can swap your parts over to

[morrag]

Rod, your set up as shown should not be giving you the probs, you are having, even without the expansion tank fitted, so, I believe most definitely your troubles lie elsewhere.Digger, as he's said, has a perfectly "workable" straight forward, virtually "ex-works", set up, so....you know what you must do!.....Morrag

[Manky Monkey]

Got to admit, this does seem to be getting overly complicated! I always built my trikes by the Try it & see method. A standard Reliant radiator tucked up as high under the headstock as I could get it, (height usually dictated by whether the forks/yokes foul on it on full lock). Small electric motorcycle fan behind it. Top & bottom hoses. Job done. Even my green one, with the coolant running through the bottom frame tubes to a rear mounted Ford Fiesta rad with a Renault fan, worked fine, despite the rad being several inches below the top of the engine's water jacket. Just meant I had to jack the back end of the trike up so that the filler neck was the highest point in the system, to bleed the air out of it.
It does sound like the system's getting pressurised somehow, or there's an air-lock somewhere.

[andyrennison]

There seem to be 3 reasons most people think may be causing the problem:

1. Engine is developing normal heat, cooling system cannot cope (Discounted by most commentators)
2. Engine is developing more heat than normal, cooling system cannot cope
3. Engine is leaking gasses in the cooling system, causing pressurisation and venting
4. 2 + 3 are both happening

So, how can Rod test these hypothesis

Number 2 Is there any way to prove or disprove this?
 

• At what temperature does the system vent Rod?
  
• Is the temperature at which the system vents the expected temperature the pressure cap that is fitted?
  

Number 3 is there any evidence to refute it? 

• Would running the engine at high revs without load, (stationary) cause the same pressurisation as if the vehicle was travelling ?
• Rod, didn't you get pressurisation from combustion gasses checked locally ??

[spanners]

has the water pump impeller come loose on the shaft ?