1985 Bayliner Volvo AQ125/270 overheating problem

[zakaih7]

posted August 19, 2002 11:46 PM <br />I have a 1985 Bayliner with a Volvo Penta I/O AQ125/270 that has overheated all year long. After extensive repairs and expense I have given up on the local dealer.<br />The following have been repaired or replaced with no improvement.<br />The raw water pump impeller and seals and water tube seals. The lower units water tube and seals. Radiator cap, pick up tube seals and bushings and bearing. New anti-freeze mixed at 50/50 ratio. Currently there is no thermostat in the engine but I will install one tommorrow and try it again.<br />The unit only overheats with the engine rpm above 3300 or when pulling a skier above 20mph. The faster I drive the quicker it overheats, and conversely I can run all day long under 3000 rpm and it never gets hot. When hot it has a great loss of power and rpm's drop as well.We were told that the lower unit was probably sucking air and that is when we replaced all the lower unit seals and bearing. We have run it with a garden hose hooked up to the intake port hose and it will not overheat at all! No matter how high the rpm's and therefore I think it has to do with the load or torque demand placed on it.<br />Any help would be greatly appreciated and if anyone is hesitant about volvo lower units and has any questions about them please ask. We have devloped quite system for removing and repairing it and can do most repairs in about an hour now. haha What a way to gain experience.<br />We thought the overheating was initially from a low grade octane gas that was accidentally put into the boat. We competely drained the fuel system and put top quality premium fuel back into it and it did help by about 10 degrees or so.<br />The engine seems to be running about 230 degrees when very hot and will idle along at 170 the rest of the time.<br />Any one experiencing the same and having answers would be great.<br /><br />Thanks for the help.<br /><br />Michael<br />Zakiah7

 

[chads15]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Is this a Closed cooling system? if so I would be checking the heat exchanger. Perhaps it has ingested some sand/silt or seaweed.

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Yes it is enclosed, but i took it off and checked it a couple months ago and it ws very clean. I just took it off again today to double check myself and it is still clean.<br />I also removed the exhaust manifold today and checked it to make sure it was flowing the raw water properly. It was fine as well.<br />The block appears very clean and the enclosed water systems water pump appears to be working as well.<br /><br />As you can see this is a real head scratcher.<br />Any further ideas or help will be greatly appreciated.<br /><br />Michael<br />zakiah7

 

[bbracken]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

1. Praise for giving a clear, complete description of problem and what you've done.<br /><br />2. I'm not a boat expert, so feel free to disregard my comments. I do have some experience with infernal combustion engines in other configurations.<br /><br />3. If the engine overheats, either a) the cooling system is not removing the designed-for amount of heat, or b)the engine is producing more heat than designed. (i.e. for a given amount of fuel, less useful work, more wasted energy).<br /><br />I'm not going to address a). You have obviously done your homework, gotten some good advice, the forum is loaded with suggestions, and your cooling system sounds healthy.<br /><br />Regarding b), there are two main reasons for producing excess heat: late timing and lean mixture. Usually we don't monkey with the timing or carb or injection system, so there is no reason to suspect them of having changed. I find two of your observations interesting. The "great" loss of power (wasted energy), and the bit about the gasoline helping somewhat. Oh, and your comments about torque also.<br /><br />This all is consistent with preignition or detonation. You say "all year long". Was the boat in storage? repaired? tuned up?<br /><br />I would check the timing first. Easy. Then look for a fuel problem. Not as easy. Check the spark plugs to see if they are running hot (light color, rounded electrodes, maybe micro-blistered surface). Check fuel filter, air filter, float level (if carb), crud in float bowl.<br /><br />I took too many words-could have just said "Hey, zakiah, check the timing and carb."<br /><br />Let us know how you make out.

 

[clanton]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Splice in clear hose just before intake of raw water pump, bubbles will indicate air leak.

 

[ODDD1]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

I am lining up right behind clanton [lol]..have seen many,many of these units sucking air through the water elbow gasket [located between uj bellows an exh bellows]and giving your symptoms, running cool off plane, overheating on plane/under load..........

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

I will be reassembling the the engine tommorrow and will get a clear tube into the system and watch it.<br />I'll let ya'll know the results. I pulled the head and the water pump (anti-freeze) tonite and will check them out in the am as well.<br /><br />It gave us a chance to clean up and paint all the bolt on parts anyway. Looking very good!!!<br /><br />Thanx for the ideas.<br /><br />Michael<br />zakiah7

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Hey all<br /><br />We didn't get it finished tonite so I'll update ya'll maybe tommorrow.<br /><br />The head was as clean as a new one and the intake tubing was clear as well.<br /><br />Michael<br />zakiah7

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Well we got it back together and tried the clear tubing to see what we could. Guess what, at higher rpm's there was a ton of air coming into the intake side. I took a hose and ran water on all the out drive areas that could suck air and it was the next thing below the hose neck???? What is up with that? We can't seem to see any kind of gasket or seal in that area at all in the book and there sure wasn't one when we took it apart the first time.<br />The air leak is between the intermediate housing turning boss and the steering yoke. These may not be the proer terms so if a pic would help we will get one on here in the am when we have some light.<br />Could we have improperly installed the yoke seal upside down or is there something we just don't understand?<br />Which way should the o-ring portion of the yoke seal be installed? Oring up or down?<br />The book doesn't say the and the old one was so bad we didn't even know it had an o-ring on it until we got the new one.<br />Any help would be really nice about now as we are thoroughly stumped by this air leak.<br />I am really glad u guys gave us the clear tube idea tho as it has helped determined what the cause is. Now for the fix.<br />We wait anxiously.<br /><br />Michael<br />zakiah7

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

It is Saturday Morning.<br />Sure hope everyone isn't on the lake! lol<br /><br />Michael<br />zakiah7

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Hi Everyone<br /><br />I think we found the problem.<br />When we took the intake neck off the out drive, we found that it wasn't a very good fit. So we installed a new on and siliconed the tar out of it. Wow no air bubbles at all at high rpm's.<br />We are headed out to the lake to try it on the water. Ill let u know later tonite if we had success or not!!<br /><br />Michael<br />zakiah7

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Thank you to everyone who offered help on this problem.<br />It is running better than when we bought it!!!<br />Temp is 181dgrees wide open. <br />The intake neck repair is what did it.<br /><br />Anything i can do to help let me know.<br /><br />Michael<br />zakiah7

 

[ScooterZ]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

I have a similar situation.<br />86 19' Bayliner Capri with a Volvo Penta 275 drive.<br />Idles cool and heats up rapidly on acceleration.<br />The engine also seems off on the timing. Very little power and a lot of hesitation<br />When it was ran hot it back-fired through the carb. I tried to loosen the distributor and cannot even get it to budge. The previous owner had just about the works replaced (in the cooling system)and I just replaced the exhasut manifold it was cracked I thought that would have cured the problem. But at higher RPM's it still runs 220 degrees and up. Does any one have any other suggestions.. I am trying to locate the area that was the sollution to your problem.. But I am not sure where you are talking about? Can you send a pix or a link to a pix of that area! <br />Thanks for any help<br />Happy Boating...

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

ScooterZ<br /><br />The raw water intake on a 270 out drive has a black hose clamped to a neck similar to the upper radiator hose on a 350 chevy engine. It is smaller and on mine it is between the upper ujoint bellows and the lower exhaust bellows. It is about one inch in diameter. The neck itself was the problem on mine. There is an odd looking gasket with a built in oring that was allowing the intake to suck air at higher speeds. I removed the neck and siliconed the gasket and reinstalled it and let in cure for a couple hours. That fixed it completely. No bubbles at all.<br />I would recommend installing a clear hose under the engine doghouse. Put it between the raw water intake and the raw water pump. I used a very large laundry tub with the prop removed to test run the engine and lower unit. The bubbles were very large and easy to see.<br />Your Unit may be different than mine but I'm sure a book on it is available so you can identify the corresponding parts.<br />You should also check the following:<br />1. Intake screeen or filter.....Plugged?<br />2. Enclosed cooling system heat exchanger must be clean.<br />3. The thermostat should be working properly.<br />To check thermostat use a thermometer and put the thermostat in a pan of water. Heat the water slowly to the proper operating temperature while observing the thermostat. It should open up and then add some ice afterwards to cool it down and it should close as well.<br />4.Both the raw water and the fresh water pumps should be working. Circulating fluid.<br />5. The outdrive raw water pick-up should be free of debri and not plugged.<br />6.Check the timing with a timing light.<br />7. If the engine is carburated, adjust it per manual.<br /><br />There are other things I'm sure that should be checked but these are the most likely in my opinion. A good service manual should be the first thing any DIY should spend his money on. They aren't the answer to all problems by any means but they can sure get you headed in the right direction.<br /><br />My email is zakiah7@yahoo.com. If you need anything else feel free to email me.<br /><br />I don't have a scanner yet so I can't send a pic.<br /><br />sorry<br /><br />Michael<br />zakiah7

 

[johnkc]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

one thing that needs to be looked at when this gasket with the built in oring fails is the bushing just below the gasket . if the bushing that supports the stainless water tube is worn out the tube moves around and takes out the gasket with the built in oring . so zakiah7 if you encounter a over heat again look at the gasket and bushing .

 

[zakaih7]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

Thanks for the heads up....the bushing on mine is in good shape!<br /><br />Michael<br />zakiah7

 

[ODDD1]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

John is absolutey right...with the elbow removed, you can grasp the lower unit and watch the shaft flop around in the bearing! a new gasket will buy you some time, but you must keep a suspicious eye on it...

 

[ccarper79]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

I have a aq125a with a 270 outdrive, I have put the clear hose in and tested with the boat in neutral choking it up..and did not see any bubbles..but I continue to lose antifreeze out of the cap..Yes I replaced the cap with a volvo new cap still didnt help the boat idles at 200 degrees and climbs a little bit but deosn't go above 208 even when plaining. any help??

 

[captmello]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

I have a aq125a with a 270 outdrive, I have put the clear hose in and tested with the boat in neutral choking it up..and did not see any bubbles..but I continue to lose antifreeze out of the cap..Yes I replaced the cap with a volvo new cap still didnt help the boat idles at 200 degrees and climbs a little bit but deosn't go above 208 even when plaining. any help??

ccarper79, you need to start a new thread of you own.

BTW, welcome to Iboats.

 

[bobward737]

Re: 1985 Bayliner Volvo AQ125/270 overheating problem

I'm assuming you've had the boat for a season or two and ran fine before..

If so, how's your impeller? New ones are cheap and mine gets changed every season.

The cap blowing is too much pressure (a.k.a. temperature. Mine last "blew" when my last impeller failed (before I replaced them annually). That's how it is designed to work. Your temp guage may be off, especially if it is the original temp bulb.

Take a look at the impeller - pull it out and look at it.

Good luck!