AQ125A Questions -overheating? oil pressure

[TralierTrash]

After registering on the site I realized that I had spelled my user name/screen name wrong. Sorry


I hope that I'm not out of line by making my first post a question. I've been reading these posts for weeks and have had some great success making repairs based on other threads.

However, I'm hoping to find some specific help on two problems that I'm having, or think that I'm having.

So far the repairs/maintenence that have been done:

Impeller
Thermostat
points
rotor
plugs
wires
coil
carb rebuild
new v belt
fresh fuel

Now on to the issues:



1) Oil pressure. What should the idle and operating oil pressure of an AQ125A be?

2) Again, assuming that the gauge works properly I'm finding that my water temp climbs over 200 idling in the driveway. I do have a freshwater hose hooked up to the motor. I've replaced the impeller, flushed the cooling system multiple times, I've even replaced the thermostat. I'm getting plenty of water moving through from the hose. When out on the water under cruise or load the temp quickly climbs to 250 or so and does not come back down.


Thoughts, suggestions and diagnoses are certainly appreciated.

 

[Starflight]

Re: AQ125A Questions -overheating? oil pressure

oil pressure should be between 36 and 87 when engine is up to normal operating temp. t'stat starts to open @ 180F and is fully open @ 198F.
You need to confirm the guage reading. Use a infared temperature gun and point it in the same direction as the temp sensor location. If guage is correct, you need to look for leaks that may be sucking air before the raw water pump causing low circulation. a common place is the hose connected between the transom shield and the outdrv. may have corrosion at the hose connection. you did check the raw water strainer right?

 

[TralierTrash]

Re: AQ125A Questions -overheating? oil pressure

Thanks. I don't believe that I'm taking in air anywhere, not to say that to be fact but I've read others who have mentioned such. I don't see any water leaks and it seems to be flowing water well from the hose/muffs.

The oil pressure on the gauge indicates a reading near the top of the gauge perhaps 70 psi? If this is correct what would cause high oil pressure?

Thanks for the help!

 

[Starflight]

Re: AQ125A Questions -overheating? oil pressure

the oil pressure i wouldn't be concerned about. my aq130 runs really close to 80 psi. when warm.
the temps your guage reads would have me looking hard for the problem. it shouldnt be much more than 200 deg, but 250 is really a problem. as i stated earlier, you need to confirm the guage reading. if accurate, i would use the clear hose trick before the raw water pump and put the boat in the water and look for bubbles in the clear tubing. the test on muffs may not show problems because the suction side of the pump is in a positive pressure. with the boat on the water pulling water from the lake it will be under a negative pressure and air induction can be a problem. give it a try. what will ya have to lose?

 

[TralierTrash]

Re: AQ125A Questions -overheating? oil pressure

Thanks so far for the help.

I also just noticed that I misspelled "trailer" in my screen name. Ha, for some reason I didn't catch that.

Oh well, so back to the boat.

I thoroughly flushed the cooling system until the water ran clear. It came out as a milky brown water on the first few flushes. I have filled with 50/50 antifreeze.

I also did replace the temp gauge and it certainly is more reactive to the temp.

It hasn't been back in the water since last week, but i've been running it on the muffs with the lower pickup plugged. It seems to be putting a fair amount of water through the impeller pump.

Okay, so it's been running in the driveway and within three minutes the temp shot up to about 230 when I cut the engine off.

I should be getting enough water from the hose into the motor.

Could the water pump have failed? I wouldn't rule it out since I've replaced about everything else on that motor so far.

Is there a way to test a water pump prior to removing it?

Would you assume at this point it would be the water pump?

 

[Starflight]

Re: AQ125A Questions -overheating? oil pressure

I'm only typing from auto experiance, because i've only delt w/ raw water cooled engines...it seems to me that you should be able to see your coolant circulating (like a radiator in a car) if you keep the cap off while engine is running and up to temp. The only water pump failures i've had were seal problems. never had 1 not circulate. the shaft is stainless and the impeller is bronze or brass if its a marine pump and should not corrode to a point of not being able to pump. w/ that said, i don't think the pump is the problem.
scale buildup on the raw water side in the ht exchanger or blocked passages would be more likely the prob. if all else is good.
also.....have you checked or replaced the temp sending unit? that would be my next move if not checked w/ a temp gun.

 

[TralierTrash]

Re: AQ125A Questions -overheating? oil pressure

Thanks for the info Starflight.

This issue is elusive to me.

I've replaced the thermostat, which I'm confident is in right because it only seemed to fit in one way. I've flushed the entire system multiple times until it ran clear. I even used a commercial Prestone flush solution.

I'm changing the oil again to see if perhaps there is some correlation between the excessive, heat and the oil pressure.

I don't have an infrared gun, nor do I know anyone that has one. I've heard a few people reference this, but I don't intend to purchase such equipment for a single use.

I did replace the temp gauge and it did confirm that my old gauge was properly showing that the engine is running hot. Of course it could still be the sender, but aside from that It does seem the motor is running hotter than it should.

Any and all suggestions and thoughts are welcomed to this!

Thanks one and all!

 

[jigglestick]

Re: AQ125A Questions -overheating? oil pressure

the infrared temp guns are getting cheaper all the time.
I think I saw one at napa for under 40.00?
dont quote me.
I would have to believe though, that once you bought one, you would find a ton of things to use it on.
in my opinion, worth the relatively small investment.

one thing I wanted to bring up as I have read a couple threads on overheating, is that I have three volvo engines sitting here at my place.
one in my boat, one for parts or rebuild which is basicly the same motor as the one in the boat.
the third, is the orriginal motor that came out of the boat.
not sure what model it is, but I know it is a 90 horse and though fairly similar to the aq 130 in my boat, there are distinguishable differences.
the thing they have in common is that they draw water from the lake to cool the motor.
in an effort to cure a leaking frost plug situation I removed a plug from the 90 horse.
what I found was a heavy deposit of sand inside the block behind the frost plug.
I know these are sediments from the raw water being drawn in.
my pertinant contribution to this and related topics is that when all else has been examined and decided upon not being the cause of the problem, I would have to think that these sediment deposits inside the engine block could quite often be the culprit of excessive heat.
not saying this deffinately is the cause in these cases, but it did occur to me that those misplaced areas of beach simply can't be good.

 

[Starflight]

Re: AQ125A Questions -overheating? oil pressure

jigglestick...he has a closed loop cooling system. raw water is only used in the heat exchanger and to cool the exaust. not the engine.
check this out....for the price, ya cant' lose. i paid about $110 for mine, but its a commercial unit i use everyday 4 work.
http://cgi.ebay.com/ebaymotors/NEW-...tegoryZ43991QQihZ014QQitemZ330136584390QQrdZ1

 

[Starflight]

Re: AQ125A Questions -overheating? oil pressure

also, usually the oil gets thinner when the engine gets hot, and pressure goes down as a result.

 

[TralierTrash]

Re: AQ125A Questions -overheating? oil pressure

Okay, so I bypassed the muffs and hooked up the hose to a clear tube and connected directly to the copper pipe leading to the raw water pump/impeller.

1) Water flow was dramatically increased and no air was getting into system.

So i figured this was a fix for the problem. Alas, twas not.

The temp gauge climbed right up to where it was before.

2) I could hear the hose water pressure making a groaning noise at the raw water pump.

To recap, so far the new items are.

a) water connector on outdrive, new rubber seal as well.
b) new radiator cap
c) new impeller
d) new impeller cover seal

I also have checked all clamps.

So once I had the hose water hooked up directly under full pressure It should have kept the temperature at 180?

 

[jigglestick]

Re: AQ125A Questions -overheating? oil pressure

can you check inlets and other small passages that chunks of the inner layer of hose hasn't come loose and made it's way to the first tight corner and is restricting flow?

with as consistant as your problem, I say when you find your problem, it will be obvious.

good luck!
keep us posted.

 

[JAL51974]

Re: AQ125A Questions -overheating? oil pressure

This overheating can drive you crazy and fry that engine.
Even if you have a tiny air leak in that system it would be enough to create those high temps. you must check the entire line from the outdrive up to the raw water pump.

"so I bypassed the muffs and hooked up the hose to a clear tube and connected directly to the copper pipe leading to the raw water pump/impeller."
when you hook up the clear plastic pipe on the water intake line the point is to run it on the muffs-if air is leaking from the outdrive side of the line you will see bubbles in that clear plastic. Then you know it is coming from one of those gaskets/seals/or the water neck fitting.

There is also a washer behind the raw water pump that goes bad, leading to air leakage, you have to remove the pump itself to check that one. Keep at it you will find the culprit! Took me a good part of last summer to find mine. Check the previous posts on this problem and I wrote about how I finally diagnosed and fixed the air leak.

Joe

 

[Mischief Managed]

Re: AQ125A Questions -overheating? oil pressure

The heat exchanger may be full of crud on the raw water side (the inside). It's hard to flush but muriatic acid will do a super job. Beware that it's nasty for aluminum, will bubble over when you pour it in and can hurt your eyes and skin.

I'd take the exchanger out of the boat to do the work and a have a hose handy to rinse the overflow off the outside of the exchanger.

 

[TralierTrash]

Re: AQ125A Questions -overheating? oil pressure

The heat exchanger may be full of crud on the raw water side (the inside). It's hard to flush but muriatic acid will do a super job. Beware that it's nasty for aluminum, will bubble over when you pour it in and can hurt your eyes and skin.

I'd take the exchanger out of the boat to do the work and a have a hose handy to rinse the overflow off the outside of the exchanger.

Alright, so the tank is flushed and In the process I found a crack on a plastic fitting on the raw water side of the system. I will attempt to correct the crack and seal it, if not possible I'll seek yet again, another part.

So, as a result of flushing the tank, which I must saw was remarkably clean considering I did find a cracked piece of plastic which I would have thought wa otherwise sound.

 

[TralierTrash]

Re: AQ125A Questions -overheating? oil pressure

Again, does anyone have a definitive way to determine whether or not the circulation pump, "Coolant mix pump" is working or in need of R&R?

 

[JAL51974]

Re: AQ125A Questions -overheating? oil pressure

that cracked fitting may be enough to cause your overheating, again it does not take much air entering that system to screw up the temp.

 

[RandyJ]

Re: AQ125A Questions -overheating? oil pressure

Just my .02.... remove the cap from the coolant reservoir while the engine is running. You'll know pretty quick. Either the water/antifreeze mix will slosh out on you or you can see it moving. I'd guess at a possible blockage in the system....especially if pump has been fixed and there is no change.

 

[TralierTrash]

Re: AQ125A Questions -overheating? oil pressure

I have licked all problems but this darn overheating.

After flushing the tank I've also now sprung leaks. I have a feeling that this has been flushed before. It's now looking like I'm in need of a new/replacement tank and the associated fittings.

I'm happy to say that it's flowing much more raw water through the system, so i believe that I may have fixed most of the inlet airleaks.

Alas, it's still overheating. 210 to 220 on idle. Quickly climbs to 240 with the gas going.