Hello, Ok. I have been building a 1929 ford sedan for about a year. I have bin having an issue with temp and its not getting better.its a 1991chevy 305 out of a RS camaro .I have an electric fan I first put in a 195 thermostat. The mechanical gauge is connected on the right side in the head beside the rear spark plug. The electric gauge for temp is connected in the intake on the right. The gauge in the head would read 230 and even flux up to 250.while the gauge in the intake would read 130.so I got rid of the thermostat and The temp in the head would never go above 180 and the gauge in the intake would read 110.give or take. So I installed another thermostat and it went up and up at one point it was 260.I am so disgusted. The odd thing was when it was Crazey hot the fan would be blowing could air and the bottom hose would be cold.I just got done replacing the water pump and put in another thermostat and still the gauge in the head reads 210 and the intake gauge is reading 140 and they both seem to flux a great deal.I drove it and let it sit and idle for some time and there's no pressure on the bottom hose its soft and wasn't that hot I feel like getting rid of the thermostat permanent. I feel like its a air lock and its because of the thermostat. Im pulling my hair out...
Was the original 305 belt setup a serpentine drive, one belt system? If so, did you change to a multibelt setup? If so, and the wp is original, the wp is turning the opposite direction. The coolant flow is reversed. Causes weird situations. peace
this engine had a serpentine setup but the original water pump is long gone.i did see some info on drilling holes in the thermostat but i also seen info on not doing that ,the radiator is sitting more above the engine then square with it.
Ypu get different readings from the heads and from the intake at the T Stat. The heads will normally read higher but there shouldn't be that much difference in temp. Have to actually checked the gauges to make sure that they are accurate? Have you tried switching locations to see if there is a big step in temp? I would switch the locations of the gauges and run it again. Just for shits and giggles.
yea i agree i don't know which thermostat to trust but its the flux in them that gets me .also the gauges showing hot and the fan blowing cold air .WTF and the bottom hose is soft and cold ,sounds like a personal problem i know but seriously .
How old is your radiator. Holding your hand against the front of the radiator, move along the fins, top to bottom, are there any cool spots. If so, have the radiator rotted out. Also check to see if your distributor is advancing. My '52 Chevy with a stock 3 row radiator had cool spots. I had the radiator rotted out. Running down the freeway, it ran at 180, but if I slowed down due to traffic, it would heat up to 210 and stay there , even if traffic sped up. I bought a 4 row triple pass radiator. At idle, it got up to 180 and stayed there. Then I checked the timing. The mechanical advance was frozen. I installed another distributor and now the car runs at 160, no matter what........ I also got a new 160 thermostat with the bleed holes.
the radiator is brand new aluminum .the timing is good and I'm fairly certain the advance is working and if i chuck the thermostat it seems fine but runs too cool . dosent seem to heat up and i understaqnd that its important to keep the temp around 190 to 210
During the late 80's early 90's Chevrolet sent a bulletin about casting flash in the 305 head causing fluctuation of the temp gage. The "fix" at the time was installing/moving the sensor/switch to the opposite head. Porknbeaner's advice is worth following. peace
If you ordered a water pump for that same 305 you would still have a reverse flow pump. I also am curious about that because your lower hose is cold. Even after flowing through the radiator that hose should be warm bordering on hot to the bare hand. You should be ordering your water pump for an 87 or earlier vehicle. 60's vehicle if you are after the short pump for clearance. Hopefully you have the right pump. Scot
i just installed the water pump it came off of a 1977 Chevy.. the one i removed came from a 1980 Chevy
Before you change any more parts, borrow, buy, rent an infrared thermometer and check the temps near the temp sensor locations. See if either of them are anywhere near right. If it is not boiling you don't have a problem. Late model stuff runs well over 212 under high pressure. I'll bet on problems with gauge accuracy.
my brother has an infrared thermometer i will get it from him and check tonight ,but the other issues ,the ,lower hose being cold and the heat coming off of radiator is only hot for a short while then it just blows cold air as if circulation stops and goes ,,strange
Only other thing I can think of right off the bat with the flow issues is to make sure the lower hose isnt pinched, or collapsing under RPM's. Throttle it up some and watch the lower hose closely to make sure it isnt collapsing from the vacuum load from the water pump.
The lower hose is the cool one. As far as I know the hot water goes into the top tank, goes down through the radiator and is returned to the motor by the lower (cool) hose. Look up a thread by Uncledaddy from a year or 2 ago. If I remember correctly (no guarantee) he had a similar problem. There are other threads too.
thermostat is cheap.buy a graduated thermostat,the one you have most likey is the reverse poppet type,opens when hot,slams shut when it gets cold.these cause the guages to jump all over the place.rad cap needs to be the highest point,or it will not purge any air out of the system.
drilled a couple holes in the stat , last night it never went over 140 but that seems way too cool,, i gotta say i am just tired of it i think i am gonna leave it like it is,, i know in the summer it will get hot either way but i am just plane sick of it,, at least its not overheating
You should only need to drill one small hole in the thermostat, to let trapped air escape. Maybe give it just one more try?
Since you are trying different things here. Test your mechanical gauge for accuracy & move it to the intake. One small hole (1/8" is the max) in t-stat. 190 ish. It's an air bleed to let trapped bubbles out of the block to escape to the radiator. The hole isn't supposed to let much coolant flow. Electrical fan set to come on at radiator temp of 220 off at 180. That's not the intake temp that's the radiator temp. Be sure your fan is capable of cooling your set-up. Your fan shouldn't run until its warmed up and certainly not continuous. Most fan relay kits have adjustable set points with a thermal switch that slips in the fins of the radiator. You could also look in the "Napa Big Book" and find a thermal switch that suits your application. Verify flow thru the radiator first, to save your sanity while finding the problems.
whats the worse that can happen if the engine temp never goes above 150 its running synthetic oil -too cool has to be better then too hot- i may just try one more time and drill a smaller hole in a new thermostat
The rings/bores will wear faster, not a problem if you don't put a bunch of miles on it. Also the heater won't work too well, not a problem if you don't have a heater or don't drive much in winter. But I'd fix it just to make it right.