Hi all,

Together with some other students from Delft (The Netherlands) I am the proud owner of a Volvo 740 GL from 1985 with B230A engine.

Before we bought it, we went for a test driven. After the engine had warmed up using the choke, it ran without problems, also when pushing back the choke. Starting the engine when warm also wasn’t any problem.

At the sale, we agreed that the seller would get it through general inspection before we bought it. During this inspection, they found that the CO was higher than legally permitted, for which they adjusted the carburetor.

When we pickup up the car after this inspection, we noticed that the car ran less smooth. Even with a warm engine, we needed the coke and also during driving the engine sputtered when we turned off the choke. When shifting down, the engine drops out for a second, and when pulling away, the engine barely responds to the gas. On our way back, we had to use the choke for the entire journey.

On the way home, the pre-heater hose came loose on the side of the air filter, but as far as I can find, this shouldn’t have any impact when the engine is warm – apart from that it looked quite catastrophic when we saw a hose dropping down under our new-bought car.

Because the car is somewhat drivable with the choke, combined with the fact that the carburetor (a Zenith 175 CD) was just adjusted, I suspect the problem lies in the fuel fixture.

Before we start adjusting the carburetor ourselves, I’m curious if you have any advice. Do these symptoms ring a bell for someone? Is adjusting the carburetor indeed the right approach, and if so, do you have any tips on what to look at?

Huge thanks in advance!

Kind regards,
Tim

 

Unfortunately all Volvos sold in the US since the early 1970's have been fuel injected. But it sounds like you have a simple carburetor problem which should be fixable by any mechanic who is familiar with Zenith carburetors of that era, a simple rebuild may be what you need at the worst. Probably not easy to find many shops who do this but there should be some, other makes used the 175CD besides Volvo... If you Google that carburetor you'll get a lot of info re options like new, rebuilt, repair parts and instructions, etc. Good luck!

 

oh dear i had those zeniths on our '69 145.. they were very difficult to get right, and once you did it's better not to touch them!
an old trick to pass inspection was to lean the carb out .. inspect it... then turn it back up again. perhaps
that is what your seller did and another adjustment is in order which might cure the problem.
or as lev pointed out, a rebuild.

 

Has the oil level in the damper been checked? It's not unusual to have leakage around the throttle shaft in thirty six year old carburetors. Spray some carburetor cleaner around the exterior of the shaft and see if the RPM's increase. If so you have a leak.
Enrichening the mixture as suggested is the cheapest fix. Without your own CO meter it is difficult to see how rich you can go legally.
Joining a local Volvo owners group would be good investment. Someone who has been to the dance can teach you the steps.
Welcome.

 

All good advice here so far - I will only add how neat it is that a group of students pulled their money together to buy an old Volvo. Sounds like something I would do in my youth - you should make a movie. Anyway, good luck sorting your carb problem. I work on VW carbs all the time. Adjusting the mixture screw as silvermine mentions above would be my first step. Google your carb to learn how. Here are some other questions you could answer if the problem persists. Does the problem change when the engine is cold or warm? Is the idle speed seem to be higher or lower than before you took it in? Any loose vacuum hoses in or around the carb? Did the inspectors take anything else apart?

 

+1, in particular looking for intake air leaks. Check vacuum lines, spray around with carb cleaner around the base of the carb and manifold etc.

 

Good news, we found the problem! after struggling with the carburetor adjustment tool for one and a half hour, we decided to open the carburetor. When we did this, we found that the needle, which is normally attached to the part that screws up and down, was just laying at the bottom of the carburetor, which explains why it was running so lean.

We screwed back the needle in the intended location, reassembled the carburetor and indeed, the engine runs as smoothly as we knew it from the test drive

Thanks a lot for all the advice!