Bypass cooler on my Volvo?

[d_glover25]

I have a AQ151C Volvo with a 290 outdrive that constantly gets milky oil. It was drained repeatedly and ran fine, after 5 mins of operation, milky oil again. Searched the block and lines and found no leaks or cracks. The guy who does our signs has the same engine with the same problem. He said all he did was bypass the cooler and the problem was gone and he's had no problems. Any advice on the procedure or hose/conector type. Anything bad that can happen from doing this. Engine is cooled by water as well correct?

 

[Haut Medoc]

Re: Bypass cooler on my Volvo?

I'm not a Volvo guy, but exactly what 'cooler' are you referring to?....
This is a Don S question....
In the mean time it would be helpful if you could post your engine serial #.......

 

[HT32BSX115]

Re: Bypass cooler on my Volvo?

"The Guy" was probably talking about your oil cooler/ heat exchanger.

You could do this to determine if it is leaking water into the oil.

If it is leaking it was probably caused by freeze damage. I wouldn't run it permanently without the oil cooler though.

There's usually several of them for sale on ebay.

Beware.

You may be buying one that has the same problem as the one you replace!!

An easy way to check the oil cooler would be to remove it and connect a simple 0-30 psi air gage (from harbor freight etc) to the oil input or output connections and put a valve and an "AIR" quick disconnect on the other side.

USE THE REGULATOR on the compressor AND SET IT TO about 10-15 psi FIRST.

Connect your air compressor to the other side with the valve and quick disconnect. (Have the valve closed before you connect)


After you connect it and verify that you have the regulator on the compressor set to about 10-15 lbs open the valve and allow it to pressurize the heat exchanger.

Close the valve you put on the quick disconnect side and remove the air hose.

The valve will trap the air inside the cooler.

If it's leaking, the pressure will drop as soon as you close the valve. If not, (and all your connections are tight) the cooler will hold pressure indefinitely.





You're absolutely sure the block is NOT cracked?



Cheers,

Rick

 

[bruceb58]

Re: Bypass cooler on my Volvo?

You can pressure test the cooler to determine if it is leaking.

 

[d_glover25]

Re: Bypass cooler on my Volvo?

Yes, I am talking about the oil cooler

 

[DHPMARINE]

Re: Bypass cooler on my Volvo?

If you bypass the cooler (as a test only) ,and no longer have water in the oil ,I'll bet the cooler leaks oil where you removed the water hoses.

DHP

 

[Don S]

Re: Bypass cooler on my Volvo?

You aren't going to get any water into your oil while the engine is running. That oil cooler will have maybe 1 or 2 psi of water pressure and 50 to 60 psi of oil pressure. Guess which way it will leak. So oil WILL leak into the raw water and should be seen as a sheen on the water when running. When you shut the engine off, they water can leak into the oil. Then, when you start the engine the water and oil will mix.
You really should have the oil cooler in there on those engines. They normally run about 190° and the oil is much hotter. That is why they went to the coolers. But if you only do short runs and a small number of hours a year, you would probably not notice it..
But with the way those water pipes hook up, not sure how you would go about bypassing it and expect it to last.
You can still buy the oil cooler tube bundles called inserts from a Volvo dealer. Of course the list price on the insert is over 500 bucks.

 

[HT32BSX115]

Re: Bypass cooler on my Volvo?

Don, of course (as usual!) is right!

The only way water could flow from the cooler to the oil is if the cooler was in the closed cooling loop. When you shut the engine down the water would flow from the cooling system to to the oil system once the oil pressure went to zero and the cooling system pressure stayed at 15psi etc.

If the Volvo is like my Merc and others the cooler is probably in the raw water line. The pressure there would never be higher than a couple of psi and on shut down, would "beat" the oil pressure to zero every time!

Man I feel stupid!......... :$ .......residual brain damage from the OMC 460!!

 

[Don S]

Re: Bypass cooler on my Volvo?

I wasn't trying to say it couldn't happen, as much as I was trying to point out (poorly I guess) is that water will leak into the cooler and the oil system when the engine is NOT running. It happens a lot. Not sure why that thin water will leak past thick oil, but it does. Maybe when you first shut it off and the oil is hot. Just seems odd that the oil would get that milky that fast.
Trust me Rick your OMC is nothing like the Volvo 4 cyl. engine. the oil cooler is a tube bundle in a housing. The housing is also the oil filter housing and sealed to the block with an oring. The oil cooler housing shown as the red #16 in the picture below, gives you some idea of how it's installed on the engine.
They are a pain to pressure test, as there are no fittings easily plugged without a lot of expensive special tools. Not even sure if they are still available.

 

[HT32BSX115]

Re: Bypass cooler on my Volvo?

Yes, that's nothing like the simple inline coolers that OMC and Mercruiser use!

That one clearly goes between the filter and the engine. (VW did something similar in the little 4 banger automotive diesels)

It appears that the water lines are rigid so you'd have to have old lines that you could hack up to make up a test set to pressurize the water side. It would be pretty hard to pressurize the oil side off the engine unless you had a couple of remote oil filter mount pads to make up a jig for the oil side.

It's never simple I guess.

 

[d_glover25]

Re: Bypass cooler on my Volvo?

So....According to Don, if the cooler was bad or couldn't hold pressure, water could leak back into the oil, just after the engine shuts down. And...like I was thinking just looking at the cooler after hearing about bypassing the thing, a pressure test would be difficult. So If I bypassed it and the oil stayed good, I could then replace the cooler and problem solved....if thats the problem? If so, would a rubber hose hold for my test run. Thanks for the info and pics.

Anyone know a Volvo parts dealer who ships quik?

 

[Don S]

Re: Bypass cooler on my Volvo?

One thing you are going to find, is that it's going to take more than one oil change to get the oil looking right.again. During a couple of the oil and filter changes, use about 50% diesel fuel instead of oil and just run it at idle for a few minutes. Then change back to straight oil. Will help get the water washed out of places quicker.

 

[d_glover25]

Re: Bypass cooler on my Volvo?

50% diesel fuel and 50% oil, like a mix?

 

[Don S]

Re: Bypass cooler on my Volvo?

If your engine takes 5 quarts of oil, put in 3 quarts of oil and 2 quarts of diesel. It'll mix.

 

[d_glover25]

Re: Bypass cooler on my Volvo?

I will try it. thanks a lot.

 

[d_glover25]

Re: Bypass cooler on my Volvo?

Well, I pumped oil and water out with the cooler still mounted, to do the test myself and only got the engine started for a few seconds. Turned it over a good bit though. When I pumped out what I'd put in it was super white like condensed milk. I bypassed water from the cooler and like DHP said oil leaked out of the cooler where the water goes in and nowhere else. The oil that came out was pretty clear too. Gonna get a new insert from Volvo. Tried ebay and came up short. Haven't found anywhere else to buy this cooler.

I'm wondering if keeping it bypassed when I put the new insert and checking for leaks is a good enough test of the insert. I would imagine all O rings would need replacing. Anyone ever ordered parts from Volvo and know if it would come with O rings or if not, where to get O rings for it. Also I don't know how to seal the lines back, any ideas?

D

 

[d_glover25]

Re: Bypass cooler on my Volvo?

any comments?