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AQ140A runs good and bad

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bhammer

New member
"Hello to all,
I have a 1977

"Hello to all,
I have a 1977 AQ140A VP with the following new parts; fresh water pump, hot spark electronic ignition,coil,plugs,cap, rotor, timing belt,weber two barrel conversion kit(not cheap),fuel filter, water separator, and new fuel lines. The timing is at 10 deg BTDC @800RPM. The engine runs fine at higher rpms, but at no wake or dock speeds(basically idle)it slowly starts to run worse, almost like its loading up, and if I try to take off it really falls on its face,sputtering away like crazy. It did the same thing with the original twin Solexs, so I don't think it's a fuel issue any more. Sometimes it'll pull out of it and sometimes it won't.It hasn't always run like this,it used to idle fine.Trying to remember back and it seems to me it all started when I installed a transducer on the transom and unbeknown to me it was shooting a rooster tail right into the fuel vent and entering the fuel tank. Realizing what was happening I installed a deflector and it seemed to work but the damage was already done, and without a water separator it made for an interesting day on the lake ,in winter, in the rain.Any way it seemed to never run right again, hence my quest to fix it. The motor seems fine other than this. All 4 cylinders have 145 lbs. of compression. Have been wondering about possible electrolysis in the head allowing coolant to enter the combustion chamber, but now I don't know because a coolant pressure test seemed fine.
Could it be the exhaust manifold? I know they go bad, but I don't know how to test it. Also noticed that #2 spark plug was a little less darker then the rest, reinforcing the water in the cylinder theory. I don't know,I'm at a loss. Any input and advise would be greatly appreciated. Thank you, Dave."
 
"Yes, you can use an automitiv

"Yes, you can use an automitive head gasket and also an automotive timing belt if you need one. Same with timing gears and belt tensioner. You may want to search the forum, I have provided links to those items in the past.

Still thinking about your first post....."
 
"Here is a question: where doe

"Here is a question: where does the vent from the cranksase go in your arrangement? On the original AQ140, there should be a hose attached to the head cover vent (forward port side), and the fumes would go to the carbs flame trap. If there is quite a bit of blow-by gas coming from the crankcase going to the carbs (single carb in your case), there may not be enough air to support combustion at idle speed. One test you can do for test purposes is to connect the vent to a longer hose and divert it overboard, then see how the engine runs. If it runs good now, then you know what your problem is.

I had the same problem years ago on my old AQ140, and short of rebuilding/re-ringing the engine (and maybe installing new valve guides) there is little you can do to fix it on a permanent basis."
 
"No, I wish it were that easy.

"No, I wish it were that easy. I tried that already. Doing that does affect the idle slightly, but doesn't solve the main issue. That was a very good idea though...

So do you believe it possible to be a problem with the head? Or maybe the exhaust manifold?

If it were a large coolant leak then it would be obvious what was wrong. But maybe if the leak were small, very small to where the coolant would drop slowly, so slow in fact that I might not notice it right away and the engine would not over heat. Has anyone ever experienced this?
I Know I keep going back to this, sorry but I'm at my wits end"
 
"If I had to choose between th

"If I had to choose between the head and the exhaust manifold, the latter would be my first bet. You may want to consider pulling the manifold and having a look. If it looks in bad shape or you see quite a bit of scale/corrosion around the water outlet area, just replace it. Attempts to clean it seldom work; and when they work they usually don't last."
 
"Pulled the exhaust manifold o

"Pulled the exhaust manifold off and inspected it. Had rust and scaly crud in it but didn't look horrible.
There was a date stamped on it, 2/14/89. I thought that was old ,so went ahead and ordered a new one and put it on and still have the same problem. Very disappointing."
 
Changing to another fuel suppl

Changing to another fuel supply didn't make a difference.
I noticed while changing the exhaust manifold that it doesn't line up very good with the pipe on the transom shield. probably 1/2 inch off and also very corroded. could it be possible that the water exiting the manifold is being deflected or splashing back up and getting in #4 cylinder?

Almost ready to give up. I just want to go fishing and enjoy my boat.
 
"HI, Came Across this issue wh

"HI, Came Across this issue while looking for help on a non-sparking Aq140...

We had an issue with the Exhaust Manifold on one of our AQ140's last year (almost sunk the boat, as water was pouring into the bilge!)

We replaced that, and hoped it would fix a similar issue as you've stated is happening to you. As you can guess, it didn't...

As a test, and on advise from a local shipyard, we took the air filter off, removed the short breather pipe, and put a longer one on, that leads outside the boat.

This has solved our rough running problems... if you like, when I'm down the yard next, i'll take a pic of the fix we've done, and post a link so you can see it


We are now looking for a more permanent fix for this, as we have a long green hose going up and over the gunwale at the moment!

Please let me know if this helps!


Regards,

Steven Davison."
 
"I'll direct this one to E

"I'll direct this one to El Pescador as I know he is good at these little OHC 4's.

I do think the crankcase blow-by could contribute..... but what about camshaft timing?
Long shot here, but if the camshaft drive belt were to have become Un-Indexed, the cam may not be following the correct indexing/timing?
Do you believe that this could cause poor low RPM operation, yet allow it to run up to the higher RPM (although you'd have to feel a reduction in power)?

Also, with the electronic ignition ignitor (assuming this is a Pertronix conversion), could excessive Up/Down distributor shaft movement cause the magnetic pickup unit and magnetic sleeve to mis-align with one another? I know that these are sensitive to mis-alignment.
My experience has shown this to normally cause higher RPM issues, rather than Low RPM issues.
But if the shaft is lifting at higher RPM (possibly creating good alignment), and if lowering at low RPM (poor alignment), could this be contributing?
Again, I know that near perfect alignment is critical on most of these.

I work on maybe two or four of these a year.... so I may not be the best one for suggestions on this engine.

"
 
"Steven, I had your very same

"Steven, I had your very same "temporary fix" in my boat for awhile, and the only cure I know for it is to permanently eliminate the blow-by gas that come through the vent. The problem is usually worn piston rings/cylinder walls. Often, a light honing of the cylinder walls and re-ringing will do the trick; but if the cylinder walls are too worn or scuffed, you may need to re-bore the block and use larger pistons. Alternatively, you could get a B21 car engine from a Volvo autowrecker and marinize it. If you search the forum, you will find some posts where I have explained how to do it.

Good luck."
 
"Hello, just wanted to update

"Hello, just wanted to update everyone,it seems that the brain can cause a person to go in all sorts of crazy directions when frustrated and desperate. After giving up and leaving her sit for awhile,I thought to give it another try and with persistance and patience I do believe I have fixed her. Turns out that the "Hot Spark" ignition was the problem.I won't give you the long drawn out version, but after going back to basics and just buying a set of points and condenser she run way way better.Idles great at around 700 rpm with no loading up symptoms. I'm so happy I could play hookie and go fishin! I tell you what,I feel kinda stupid after buying all those expensive parts just to find out it was the *$#@*%^ Hot Spark. So, beware of this, sometimes old school points aren't so bad.Happy boating everyone!"
 
"B-hammer, I'm glad you so

"B-hammer, I'm glad you solved your problem. I have read a few negative comments about Hot Spark in this forum, but virtually none about Pertronix. I agree with you that points and condenser will do the job (they did for many years. However, electronic ignition has made points obsolete for the last 20 years or so, to the point (no pun intended
biggrin.gif
) that you cannot find even one engine manufacturer installing nowadays points and condenser in new engines. Ever wondered why?"
 
"I had problems with hot spark

"I had problems with hot spark too. After replacing my points with hot spark I could not turn over my engine. I sent it back to them and they gave me a replacement, sure enough same thing. I sent emails explaining my frustration and explain to them it was a 32 year old boat. They said they reproduce my problem and told me that the shaft on the distributor was worn down and they sent me a modify one. This time it work, my boat turns over every time. Send email to hot spark and tell them you want a modify version for an older boat. They will know what you are talking about."
 
"B-Hammer, I too agree, you sh

"B-Hammer, I too agree, you should still move forward with this and place those old points/condensor in your own private museum.

Go with the Pertronix unit and you will be fine.

."
 
"Sorry for interrupting but?

"Sorry for interrupting but?
I'm not against electronic ignition, great when it works. But can anyone tell me how often is there a need to change points and cond on the AQ 4 cylinder engines? (keep the V6/8 out, a different story!!) To my experience, if properly adjusted and reasonably clean (no rust) they last about 3-5 years minimum, depending on usage. May the cost of Pertronix or any one for that sake justify the cost of changing?"
 
"Morten, I think you have answ

"Morten, I think you have answered your own question. Points work when there is no rust, no pitting, no arcing, no moisture, no grease or dust, are well adjusted, etc. With a Pertronix kit, none of the above factors are a problem (except for the original adjustment). And unlike points, electronic ignition kits do not wear out, and the ignition timing is far more stable (especially in 4 cylinder engines). Also, points do not conduct nearly as well as an electronic switch, which means a lower voltage ends reaching the coil and the spark plugs.

I think that all the above factors more than justify throwing the points and condenser in the garbage and replacing them with an electronic ignition kit."
 
"I do agree that electronic ig

"I do agree that electronic ignition is superior to points. I have sent an email to Hot Spark and they are sorry and said to send the bad one back and they will replace it with a new upgraded version. Good customer service in my opinion,just hope it works this time. I am tempted to get a pertronix kit, but I'll try Hot Spark again for cost reasons. To anyone out there be aware that if you have a Hot Spark ignition and the engine isn't running right, it could be suspect. You get what you pay for."
 
"El:
As said I'm not agai

"El:
As said I'm not against the electronics. My main question however no one answered. How long does the pints last on the Volvo 4-cyls?
I have to admit I have a hidden 'agenda'. To my experience the 4-cyl OHC's are one of the most service demanding engines on the market, and not due to its ignition system which I find rather stable. To me it looks like the timing belt and gear (crank shaft) are more service demanding than the ignition system itself, with close to shorter life time. When the points are due, it is even time to have a serious look at the timing belt and gears. A good reminder."
 
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