Logo

AQ131A running rough pops under load

dewnaz

New member
"ok, I have gone thru this for

"ok, I have gone thru this forum trying to find bits a pieces to my motor's problems and many have helped greatly.. Last summer the problem started all of a sudden during acceleration under load the motor popped and sputtered like something broke, and would not get up on plane without much backfiring and rough running. The boat still idled perfectly but rough under load. I have since rebuilt the carburator, acceleration pump pumps lots of fuel and carburator seems to perform correctly. New points, distributor cap are new also. This summer I have installed new pertronix electronic ignition, pertronix coil, spark plugs, plug wires, checked all timing marks and timing belt for slippage hoping that this would solve the rough running situation. Upon starting the motor the motor runs rough at idle now and was difficult to get it up to about 2000 rpms with the muffs on. What is the next step to check out? Distributor weights or springs? Timing?Valves broken or something internal? Leak down test? Am stuck at this point until I get the sea water pump carrier from VP I can't run the engine, but any suggestions would be great. thanks"
 
"Replace the timing belt, cran

"Replace the timing belt, crank shaft timing gear and tensioner. Have seen too often on the forum:

'checked all timing marks and timing belt for slippage hoping ... '

And it ends up with the belt anyway. Only way to properly check is to replace!"
 
"The cam timing mark, the inte

"The cam timing mark, the intermediate timing mark are right on at #1 TDC, yet the crank timing is to the right approx. 1/2 inch. Is this ok and will timing with the distributor make up for this? Hesitant about breaking off more bolts if not needed to replace the timing belt. Am already waiting for sea water pump bolts and corroded carrier part from VP."
 
"update... did compression che

"update... did compression check...160-165 on cylinders 1-3.. 0 on #4. What am I looking at next.. Is this worth fixing, etc. Any experience with this on 4 cylinder VP's would be appreciated."
 
"hi there, i had the same prob

"hi there, i had the same problem with my 6 cylinder and the problem was a valve was stuck..........head off, get it re-seetted, new valves on that cylinder, back together and it was fine. cost me around £1200 GBP. hope this helps buddy"
 
"update...after doing the comp

"update...after doing the compression test, took off the head and found edge of the exhaust valve broken off in the #4 cylinder. Am taking it to a machine shop now..hopefully will be good news and I can put it back together and have it up and running by the 19th. Is there anything else to look for now that I have the head and exhaust manifold off?

On another note, has anyone out there done the Weber carburator conversion on the 4 cylinder volvos. I am contemplating this move since I have motor torn down. thanks for any input."
 
"dewayne, search the forum for

"dewayne, search the forum for the Weber conversion. Some forum members have done it and reported positive results.

When you have the head out, you may want to ask the shop to look for corrosion/wastage around #4 exhaust port. If it is found in bad condition, they can either build it up with TIG welding, or mill it and make a steel insert."
 
"Thanks El P, I will talk to t

"Thanks El P, I will talk to the shop in Bellingham, Wa. about maybe welding up the #4 port. The cylinder has had the round steel sleeve put in the head sometime in past before I owned the boat. The steel sleeve looks fairly good, but is starting to pit out and corrode, so hopefully it can be touched up and last for another 10-15 years. I am having the shop do a complete valve job as the #3 exhaust valve also had a crack in it.

Does anyone have the part # for the intake manifold gasket on the aq131a, or does it come in the gasket kit?

On the Weber conversion topic, I talked to Weber about the jetting, and they said that they set it up for sea level up to 300ft. So my question is if I am boating in high lakes up to 1000 ft. do they put in a different jet or air nozzle? I will call and talk to someone. Still hesitant as this is lot of $$, but would be fun to install and see the result of the new carb with the Pertr. electronic ignition.
happy.gif


Also, if I change the prop (the boats is in need of a new one) how do I know what is on the boat and should I prop up or down in pitch, diam. etc. I can't see on number on the old prop at all. Any help would be appreciated."
 
Back
Top