gretchen/jason Posted March 22, 2008 Share Posted March 22, 2008 Ok to start of i have a new aluminum pump anti cavitaition high flow , also a high flow t stat . New radiator only 1,000 miles on it not cloged . New radiator cap " i have several caps " thought i bought a bad cap so i have 4 of them . Engine has 400 miles on it no clogs or anything like that . With the cap off i can clearly see the fluid flow no problems there . When i put the cap on and rev the engine it sucks the hose flat . Its a new hose at that this is the upper hose im talking about , i was told the rad cap was bad even though it was 2 weeks old i just bought it . So i got another and guess what same deal and to go along with this problem when at idle with the cap off the car cools itself just fine . Reinstall the cap and bang 210-230 degrees all this with a 160 degree stat . Same cruising through town it gets hot " 40 mph equals 1,700 rpms " On the highway its great cools fine . I do have a 6 inch crank pulley and a 6 inch water pump pulley should i get a smaller water pump pulley for the cooling issue ? As for the rad hose colapsing i have no idea what it is . I do have some of that solid chrome flex hose should i use it ? Jason Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted March 22, 2008 Administrators Share Posted March 22, 2008 Ok to start of i have a new aluminum pump anti cavitaition high flow , also a high flow t stat . New radiator only 1,000 miles on it not cloged . New radiator cap " i have several caps " thought i bought a bad cap so i have 4 of them . Engine has 400 miles on it no clogs or anything like that . With the cap off i can clearly see the fluid flow no problems there . When i put the cap on and rev the engine it sucks the hose flat . Its a new hose at that this is the upper hose im talking about , i was told the rad cap was bad even though it was 2 weeks old i just bought it . So i got another and guess what same deal and to go along with this problem when at idle with the cap off the car cools itself just fine . Reinstall the cap and bang 210-230 degrees all this with a 160 degree stat . Same cruising through town it gets hot " 40 mph equals 1,700 rpms " On the highway its great cools fine . I do have a 6 inch crank pulley and a 6 inch water pump pulley should i get a smaller water pump pulley for the cooling issue ? As for the rad hose colapsing i have no idea what it is . I do have some of that solid chrome flex hose should i use it ? Jason Jason, The low speed cooling issue most typically is the result of inadequate air flow though the radiator therefore not removing enough heat from the coolant. Higher vehicle speeds, more air flow = more heat transfer from the coolant through the radiator fins to the atmosphere. As for how and why removing the rad cap allows the engine to cool at idle vs when the cap is installed, the only thing I can think of is the water-pump is out-pacing what the thermostat can flow, subsequently collapsing the upper hose to the point it is severely restricting coolant flow. By removing the rad cap, the pressure inside the upper house then becomes equal to atmospheric, un-collapsing the upper hose allowing coolant to flow through it. (See below for more on the upper hose collapse issue). Suggestions for low vehicle speed cooling; 1) Improve air flow to and through the radiator as best you can. Study the Aero section of this forum as there is some REALLY good info on just this topic. 2) Be absolutely sure your thermostat is indeed opening all the way, (boil it in pan of water and visually note the amount of opening), and that there is enough room in the thermostat housing beneath the thermostat for it to open down all the way, (seen that in L-series with high flow thermostats). As for your hose collapse. My initial gut instinct is that it sounds like the high flow thermostat is not allowing enough flow to keep up with the pump. That would put everything between the low pressure side of the pump and the top of the thermostat, including the radiator and both hoses, at lower than atmospheric pressure causing the hose/s to collapse. Your lower radiator hose should also be experiencing similar pressures. Typically, the lower radiator hose has a coil of spring wire inside of it to help prevent it from collapsing and it also is generally a stiffer/thicker material which also helps resist collapsing. Bends in the hose also stiffen the hose. Suggestions for upper hose collapse; 1) Verify with a pressure gauge the pressure In the upper hose/radiator/lower hose. 2) Be absolutely sure your thermostat is indeed opening all the way, (boil it in pan of water and visually note the amount of opening), and that there is enough room in the thermostat housing beneath the thermostat for it to open down all the way, (seen that in L-series with high flow thermostats). 3) Check to see if the upper radiator hose is just too soft to begin with. 4) Possibly install and upper hose with the coiled spring in it or install a coil in yourself to keep it from collapsing, or a rigid upper pipe. At this point, that is all I can think of. If anything else comes up that might be of help in diagnosing this, or you perform any testing, be sure to update. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 22, 2008 Author Share Posted March 22, 2008 I have tested the t stat in a pan of water on the stove when i bought it , i also measured how much " taller it gets " when opend . I measured my intake where the t stat goes and had enough room for it to open . When i ordered the water pump " high flow " i bought the t stat recomended for that pump . I do have 2 yes 2 radiator caps on my cooling system as i bought a in line filler and one on my radiator . For a update I was bored since my post and moved my coolant overflow hose from the " inline filler" to the radiator filler so far it seems to have taken care of the colapsing hose for the moment that is . The hose i guess seems soft even though its a week old so ill be installing some of that stuff ya see at autozone the chrome solid flex hose . Jason Just another question , im adding this line as ive been reading through the aero section and it seems all the radiator ducting is for a vehicle at speed which i have no problem with . If no one knows this is a supercharged 383 in my z 2 row cross flow alum rad black magic xtreeme fan , pulls air through the entire rad core . My z has the factory " skid plate " the plate that mounts under the car between the rad suppor and the steering rack . Does this help the vehicle any with low speed cooling should i get rid of it . I couldnt find to much info on it even when i did a search . Quote Link to comment Share on other sites More sharing options...
Dragonfly Posted March 23, 2008 Share Posted March 23, 2008 I also have the stock lower skid plate on my car and a whole lot of ducting etc. at speed the car has no over heating issues but in stop and go traffic i.e. no airflow through the radiator it will over heat very quickly. I have a two speed fan and the low speed will easily provide enough airflow through the radiator to actualy over cool the engine. What is odd with mine is that if I use the high speed fan it does not cool the engine as quickly and seems to create "dead zones" where no air is pulled through the radiator, but thats its own can of worms. I run an electric water pump and support springs in both upper and lower radiator hoses, I also run a Nissan thermostat as it is able to move a lot more coolant than most aftermarket thermostats. Here's a pic of some of the aluminum tape I used to seal the skid plate. Dragonfly Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted March 23, 2008 Share Posted March 23, 2008 Very cool, I don't think I have ever seen the factory skid plate installed before. Evan Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 23, 2008 Author Share Posted March 23, 2008 Good idea on the skid plate except my radiator mount pokes through where you have the silver tape installed . Ive done a few more driving test seeing as at speed 60 mph and 2,600 rpms the engine cools fine . So i ran around at my usual in town speed 40 mph at 1,800 rpms and the usual happend it got hot . So i figured what the heck shifted to second at 40 mph raised the rpms up to about 2,300-2,500 rpms and the temp went down , still at 40 mph . So perhaps the size of my pulleys are turning the pump to slow in traffic so im going to try a 5 1/2 water pump pulley instead of the 6 inch pulley i have now if that helps ill then try a larger crank pulley 7 inch instead of my 6 inch and post the results . Jason Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 23, 2008 Author Share Posted March 23, 2008 So another update , after the test drive the upper rad hose , which i checked after the test drive was fine you could feel the pressure built up inside the system . So i let it cool down and for roughly 2 hours went back out to install the solid rad hose i have and the dang hose colapsed in on itself so it is now in the trash . Jason Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted March 23, 2008 Share Posted March 23, 2008 Jason, sounds like your on the right track with the pump pulley as well. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 27, 2008 Author Share Posted March 27, 2008 Ok so another update , i was on my way to work and the temp started to spike 215 degrees . Now i have about 3 feet of heater hose in my passanger floor board as my heater core busted some time back so i took some hose i had and looped it on the fittings . The stock fittings are gone so it just is a continous feed of water . Well i grabed the hose and thought it cant be 210 its barley even hot . So for some odd reason i kinked the hose and the temp shot back down to 170 very very quickly . I unkinked it and bang back to 210 and so this went untill i quit kinking the hose . Soat work i got rid of all heater hoses and pluged the ports off on the intake and water pump and so far i havent seen anything over 180 degrees . Why in the world would a heater hose cause that problem . Jason Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted March 27, 2008 Share Posted March 27, 2008 Sounds like a sizeable air pocket somewhere in that loop of heater hose. Evan Quote Link to comment Share on other sites More sharing options...
DCZ Posted March 27, 2008 Share Posted March 27, 2008 That's your problem right there. When you bypass the heater core with a loop of hose you are taking hot coolant and dumping it right back to the water pump inlet, effectively bypassing the radiator for that portion of the coolant. Plugging that bypass hose lets all the coolant flow through the radiator. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted March 27, 2008 Share Posted March 27, 2008 I had no idea thats how that system worked, good to know! Evan Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted March 31, 2008 Author Share Posted March 31, 2008 Well no new updates except that after 400 miles on a rebuilt " all new internal parts " engine my 383 has a oil leak that leaks about 1/2 a quart every 30 miles . So i riped apart my NEW engine to fix it . Seems a oil " plug " under the rear of the drivers head near the port for oil pressure wasnt sealed properly . So ends my testing of the heating problem for about 2 days . As i hope the JB weld i stufed into the spot holds or else ill have to take the head off the car " good grief " 80$ for head gaskets . But untill i tore it apart still holding around 180 -190 . I did see though when i had the intake off that the temp sensor doesnt go into the " watter jacket " All the way it sorta sits 1/8 th higher maybe a 1/16th into the adapter sleeve . So ill shorten it hope my oil leak is fixed and see what happens . Man what a bummer so far 7,800 miles with my v8 conversion and its cost me 8 grand just to keep it running , 2 gs on a crate engine from jegs that after 7 thou miles blew a oil pump then 2 grand to rebuild it then 2 g s for a super charger then now a oil leak dang " Cant we all just get along " HAaa Haaa Jason Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted March 31, 2008 Share Posted March 31, 2008 I love how you throw the supercharger into the "keeping it running total" now thats a true hybridZ member. Its frustrating, but will be worth it in the end. Quote Link to comment Share on other sites More sharing options...
1rad280 Posted March 31, 2008 Share Posted March 31, 2008 Head Gasket? Just Throwing It Out There. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted April 6, 2008 Author Share Posted April 6, 2008 God it better not be a head gasket just had the engine built only 500 miles on the thing and i used metal head gaskets . Jason Quote Link to comment Share on other sites More sharing options...
jasper Posted April 6, 2008 Share Posted April 6, 2008 I didn't scrutenize every post. What engine is in the car? Some small block v8's had reverse flow water pumps. If so, you could have the wrong pump, or be spininng it in the wrong direction. Just a thought. Aslo, some thermostats have a lower disc that functions to close off a bypass port when the thermostat opens. Make sure you have the correct thermostat! Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted April 6, 2008 Author Share Posted April 6, 2008 The block is dated for use for cars from 1970-1985 . The belts rotate clockwise . I have checked water flow as i have a inline filler and it flows corectly when the t stat opens . The t stat is a milodon high flow stat # 720-4363 160 degree stat from jegs , i boiled some water and got the t stat fully open then quickly placed it in the intake manifold to make sure it wouldnt bottom out in the intake . Keep in mind this is a supercharger intake manifold but the water jacket is the same as a aluminum intake . The water pump is a weiand pump #925-9240p in the jegs catalog . Im using a 6 inch crank pulley and a 6 inch water pump pulley , the radiator being new is from jegs cross flow #555-52007 2 row rad . Also black magic xtreeme fan that runs constantly as if i shut it down even at 80mph it will overheat . Deal is i can leave work hop on the highway doing 55 mph rpm is roughly 2,500 maybe a bit more i forget . The temp will be fine 150-165 then all of the sudden it hovers at 185 and will not go down . i can then exit the highway sit at a light temp at 180 then suddenly it will drop to 150 degrees !!!!! And all of this is happening when its 24 degrees outside in the mornings and 60 in the afternoon . This will happen at any speed highway or side streets , it was worse when i had the heater hoses atatched , it hovered at 220 degrees the would drop to 150 for no reason . To elimanate air in the system i fill the rad with the t stat removed untill i saw water in the intake then installed the t stat . The overflow tank works as designed as i check it almost everytime i go for a drive before and after . I'm actually going to try a mechanical t stat instead of the electronic one just in case the electronic one is to sensitive . And the electronic sending unit doesnt go past the thread in the intake so im thinking maybe its not in the water flow all the time . Jason Quote Link to comment Share on other sites More sharing options...
jasper Posted April 6, 2008 Share Posted April 6, 2008 Intake gaskets installed correctly? Some gaskets have block off plates in one end. I beleive they can be installed wrong. Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted April 6, 2008 Author Share Posted April 6, 2008 Yep the intake gaskets have ports on both ends not sure why as the ports near the firewall are always blockd off by the intake on every sbc ive seen so far . Jason Quote Link to comment Share on other sites More sharing options...
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