Hello all, after a bit of an absence I am now settled and ready to continue my project. 1952 Truck has been mostly stored for 18 months. The great news is it starts right up and seems to run fine. However, after it is running awhile and you are driving it bogs down/almost stalls. I suspect something with carburetor/fuel. Looking for troubleshooting ideas? Thanks, Denis
Remove the gas cap and drive around and see if it's better. Might just be a plugged gas tank vent. Heat riser may also be stuck. This will cause what you are describing.
Slows down Check the plastic gasket under the carb also if it's on the correct way look for any type of leak . More will chime in with more info just my experience with bogging down after a warm up. Best of luck to you Robert
I assume you have a stock 6 cylinder engine, if so, you should get yourself a factory shop manual. The attached is from the manual, it's hard to read but it tells you about how the heat riser works and what happens when it doesn't. This could be part of your problem along with poor quality gas we get these days. Engine gets too hot from stuck heat riser, gas boils and you have the problem you described. http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0604.htm Good luck.
thermostat? Thanks Rick, I have the book and did not think to look it up. I think my brain was in storage also. Reading this I think I will change the thermostat, I am unsure the age of it, since I have had the truck 3 years and not changed it. I see our sponsor has multiple thermostats with different temperatures. I live in CT but only drive the truck when the grass is green. Any recommendations on which thermostat? Thanks, Denis
You can flush out the old coolant and add fresh 50/50 mix of antifreeze (green stuff) and put in a new 180 degree thermostat. Make sure the hoses are in good condition and the cap holds correct pressure. Another thing to check is the distributor. Make sure the vacuum advance is working, clean and lube the governor weights and clean or replace the points. This is all covered in detail in the shop manual. Fresh gas is important too. (I'd still check the heat riser operation) Good Luck.
See the link to the shop manual in previous post. Engine Assembly 6-4 and 6-5 explains how the heat riser works along with two good pictures (Fig. 3 and Fig. 4). Read that then look yours over and make sure it works like it should.
I hesitate to get involved with something with so many variables but here goes. First check with local shops and see if one has an old engine analyzer. This will show the condition of the entire ignition system and a good tech can even read valve and cylinder data. If I were to take a one shot guess it would be a weak coil as these will perform good cold and drop off rapidly when hot. A stuck heat riser blocks the exhaust gas exit whether hot or cold so I would put it low on the list. Rig up a one gallon jug for a fuel supply and temporarily run rubber lines from jug to pump inlet and pump outlet to carb. In the carb line use a "T" and hook a fuel pressure gauge to it to check for drop off. This eliminates the fuel tank and lines as a trouble source. Start cold and let the carb bowl fill and measure gas height in the bowl. Run till it "drops off", turn off ignition switch, throw into neutral and coast to a stop. Pull carb top and measure fuel height. If lower than the cold reading the pump is weak and you're starving for fuel. Rather doubt this as usually a lean condition will cause back firing. Re-read the first line as an analyzer will give a reading on the coil, wires, points, condenser, plugs, and a good tech can see rotor and cap spikes if he is familiar with the engine. This does away with buying a bunch of unneeded parts by trying to out guess the problem. I wish I could be a swami and tell you to go directly to "this", give it a twist with a screwdriver and all would be well. We don't guess at anything but rather eliminate till the problem is found. Not the easy way or fastest but the problem WILL be fixed and done without wasted money on unneeded parts.
thanks Thanks Evan. My plan is as follows. 1. flush coolant and replace thermostat. 2. fresh gas 3. For interest sake I will investigate the heat riser if not too difficult. 4. then look at the items you suggest. This is the reason I bought this truck to work on it, troubleshoot and mostly learn. So I really appreciate all the advice. I will let you know the results.
thermoste spring The manual was helpful in explaining the operation of the HCV. IS there a way to tell if it is working correctly? What i mean is when at temperature will something move externally to show the HCV changed positions?
Yes, when operating correctly the weight will move from cold to hot. Start with a cold engine not running. You should be able to manually move the weight through about 90 degrees of arc with your fingers. The thermostatic (bi-metallic) spring should return the weight to the closed position. Start the engine. As the spring warms it should move the weight as the valve opens. Here is the "how to" from the GMC six cylinder engine which works the same as the Chevy six. It starts at the very bottom of the left column on this page: page 397 and continues on the next page (note figure 64). page 398 That said, I agree with Evan that this is most likely a fuel delivery problem, with the coil a close second. A cheap fuel pressure gauge such as this fuel pressure gauge plumbed in with a T at the carb and then hang the gauge in the cab where you can see it while driving will let you know if fuel delivery is your problem.
