Greetings. I've notice my coolant going down consistently for awhile, but only now got it up in the air to flush the coolant and do the front brakes. This is what the coolant/coolant cap looked like: http://imgur.com/gallery/wAVwH

The cap was covered in sludge. It leads to suspect there to be an oil leak into the coolant system. It could be leaking at the radiator or at the engine oil cooler. Is there any good way to test which is failing? I'll have to check the transmission fluid, the oil is jet black. There is an oil leak somewhere around the oil cooler, and the upper radiator brackets have recently failed.

Are there any good tricks to cleaning a coolant system after a leak like this? I've flushed it clear but I was thinking of dumping some sort of cleaning agent in there with water and running the engine for awhile.

How do the upper radiator brackets recently fail? And you did nothing to remediate the issue soonest?

So, the radiator is at essence, flapping in the breeze? A coolant radiator, well, even an engine oil cooler, is a frail thing. They operate fine when properly supported and move very little, yet much slow torsional distress will cause these to quickly fail and lose seal internally or lose the fluid circulating inside them externally.



I'll guess your 1993 Volvo 940 Turbo Wagon also uses the factory stock combo radiator for both engine coolant and transmission fluid cooling.



The image of coolant in the bucket show a mix of engine coolant and transmission fluid at prima fascia (first glance).

Loosing engine coolant for awhile? I'll guess no engine coolant is lost exterior to the coolant system including the engine. That would be a fail cylinder head gasket seal to the engine block. The coolant loss can occur in myriad ways, until the cylinder head gasket seal is lost.



The coolant expansion tank reservoir cap underside image show a coating of engine cylinder combustion product coating it. More than likely the cylinder head gasket has lost seal (as you note coolant loss for awhile) and combustion is blowing into the coolant system.

If this coolant mix has been going on for some time, and the fluid in your transmission appears about the same, your transmission may be toast, also.

The engine oil is jet black? When was the last time you changed it? 15,000 miles ago? A RWD Turbo Volvo automobile does not suffer neglect and abuse well. Durable they may be, yet without care and with abuse or hard driving and hung up wet, well, what you're encountering here.

Sorry for your problems. Hope the fix is not too bothersome. Be careful working with the turbo / exhaust hardware. Kroil is maybe the best penatrant, yet knock rust off the exposed studs before removal. Acetylene to heat stuck exhaust nuts may also help. New Volvo OEM exhaust studs, unless these are also now made in China.
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Thank you! Your reply was very thorough. I've only recently noticed the radiator loose, I was being foolish because I even know the problems associated with out upper brackets. We replaced the radiator before for the same thing, the plastic tank on the driver side cracked on top. I'm guessing the radiator is OK. The shift points and everything are completely the same (not perfect but good).

I am definitely changing the head gasket. A few years ago I had replaced the turbo because it was using so much oil and there was a crack in the manifold. Thanks for ID'ing the problem! It helps me out immensely. Going to change the timing belt while I'm there as well.

Some final questions, is it possible to change the rear main without dropping the transmission? Should I change the seal now so I don't have to worry later. Or maybe change if/when I replace the transmission. Similarly, very often the oil pressure light comes on. Is this the right time to do the main/rod bearings and the oil pump?

Hiya walczyk,

How many miles?

And you checked the transmission fluid in your AW-7x xx? How does it look. Confirmation as to the Tanx-Giving Day Turkey Gravy in them receptacles!!!!

I do like me a great gravy with me biscuits. Ha!

I'd futzed with the sort of feeble upper radiator supports that are long for the intercooler and the coolant radiator. They really kind of suck, yet the RWD section on the brickboard has solutions that I've read here. I'm a 240 and owlder direct experience person, however. Salt grains, please.

Waaaaaat? Oil light is on? Huh? And you continue to drive it? I dunno the oil switch threshold, yet I believe it is no more than 1 Bar (15 PSI) or maybe .5 Bar

When does the oil pressure light come on? Oil loss exterior to the engine, or engine smokes a blue-grey when cold, or steam that smells of coolant when first starting? Of you may have failed seals at the oil pump tube? A faulty oil pump, relief spring (doubtful).

This is not some Ford 351 Cleveland or Windsor. You have to separate the transmission from the engine block, the flywheel and works, and then at the engine back end is the rear main bearing seal in the rear main bearing seal carrier. So, you will need a seal press that fits. You may also want to pull the rear main seal carrier plate, an aluminum plate, and clean mating surfaces and replace the gasket. There is a similar plate at the front of these engines called the (from OHV era when Volvos engines were engines and had OHV) timing plate. It carries the front main crank seal and the intermediate (oil pump and distributor) cam seal. To remove these, you need some manner of counterhold tool to hold the front harmonic oscillater balancer crank pulley. The same goes for the two timing belt camshaft gears. Ditto on the seal press. You ain't gonna get the seal in straight with your fingers or a piece of wood. Be mindful of a groove on the inner sealing surface from the prior seal position. Use Volvo seals or Viton? I forget th brand of choice.

The timing belt you use is a round cog tooth (I believe) timing belt on 1993 and newer. Conti-tech makes OEM quality t-belts. Use the INA brand tensioner every 100k miles. Round cog belts are 100k mile belts. The square tooth belts (up to 1992?) are 50k belts. One a new belt, reset tension the first 100, 500, 1000 miles or so as they stretch on run-in.

Research the best sources of cylinder head gasket and other gaskets. I forget, yet this brickboard forum and turbobricks is replete with debates on the subject, and, iirc, there is consensus on the best gaskets, seals, and belts, and methods to use.

With low oil pressure, I worry of low end wear. You may want to check the oil filter in a tear down of ferrous metal bits on the interior side of the filter.

Research machine shops for quality head work. The head will need pressure testing and measurement. You may or may not need valve guides replaced. If you can get quality replacements any more. No valve guide knurling. Its BS. New valve guide seals. And proper shimming with new hushers from the dealer.

Have you performed a compression test at any time? Do you know compression is good and even on all four cylinders?

You could have a faulty oil pressure switch, though doubful. I worry the engine bottom end? How long does the oil light issues persist for you? When does it happen? Hos often did you change oil? What oil and filter do you use?

How many miles?

See about special Volvo tools you may need from a Volvo Penta (Marine) shop if near the ocean or great lakes or wherever maritime environment power boating occurs. Hopes they rent.

Also, the turbobricks may also help you, or last direct you to guidances useful to you.

Does that help?

Please see the: https://www.brickboard.com/FAQ/700-900/
(Click FAQ at the of every brickboard page)

Pork Chop Boy, yet again.
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I just drained the oil, and two cups of water came out first! Aggressively flushing the system might have forced some coolant into the oil. Good thing I didn't turn the engine over since then.

How did you aggressively flush the system? Was the oil fill cap off or some entry into the oil sump chambers in the engine were open? Lest blown head gasket?

Do you have a remote oil cooler? Considering new seals for that. They can come loose.

Best wishes for success!
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The head gasket didn't show any obvious signs of leaking. I used a nozzle on the end of the hose and wedged it into a heater core hose. I covered the other end so it increased pressure in the system, I flushed the radiator separately, and recently flushed the oil cooler. They all still looked gross. Blackish water came out. I wish I had an after market oil cooler. This one is bolted up to the block as an extension of the oil filter adapter.

Does it make sense for it to be the oil cooler? I'm considering removing it and hooking up water to it and checking for leaks.

I'm amazed that no one else on this forum can help this guy through some manner of response. I'm some years out on futzing with Turbos, intercoolers, oil coolers, and the sort of stupid setup of combining the transmission fluid and engine oil coolant in one. (Don't forget to change the coolant to protect the welds and other less noble metals from corrosive deterioration.


... soapbox ...

Why I drive manual transmission. Or, in Old Duke speak, from whom we should derive some manner of documented lexicon or dictionary, "three pedals". Yet what 940 with or without Turbos in North America are usually without.

Blackish water came out of ... ?
- radiator / automatic transmission fluid cooler
- engine oil cooler

With some oily residue, yes?

Use water under pressure for oil cooler leaks? Why?

The heat exchangers (coolant / transmission fluid, engine oil cooler, and possibly the intercooler) can all be tested, I guess at a radiator chop. Useing a hose with city water pressure without a seal at the ends is an inconclusive take on it.

It would have helped to have performed a compression or leakdown test of the cylinders.

A radiator shop (find an honest one) can pressure test these for you. I would consider maybe looking at the heater core for accumulated schmaltz, yet the 700-900-90 series dash so utterly sucks to get into, maybe not as bad as 240. Or leave it and let any hydrocarbons and oily residues peculate to the top of the expansion tank when you have it back together and running.

As you state earlier in this thread the engine oil is black, well, black would some out of the engine oil cooler. You'd need to use some manner of industrial cleanser. And blow out remaining water, if this is how you want to do it.

The heat exchangers (coolant / transmission fluid, engine oil cooler, and possibly the intercooler). It would have helped to have performed a compression or leakdown test of the cylinders. You indicate some manner of movement of the radiator supports. On this forum (use search) and also check here ...:

http://forums.turbobricks.com/
(You can search, yet posting requires an account.)

... so if left to rattle around, the rather brittle radiator and intercooler may flex in such ways as to lose seal. They can fracture. The coolant / radiator mix occurs in the radiator when the two separate chambers internally lose seal and mix.

However, the collected black hydrocarbon mix that coast the underside of the expansion tank seal suggests that this mixing of engine coolant / transmission fluid, and what may be very likely engine oil have been mixing for some time to coat it like that. That would appear to be engine combustion products coating the expansion tank cap.

I dunno. I'm not there. I'd scrape the coated bits and under sunlight with a magnifying lens have a close look. I can also smell the stuff and tell you what coats it. The sweet smell of the coolant, the phenolic odor of the transmission fluid, and the smell of old (I'll guess you use mineral dino oil, not synthetic, though that does not matter) engine oil in need of change some time ago.

With these items apart, I'd suggest you resolve what items have failed and whether they can be repaired or should be replaced.

Yet you've done this before, so you know the prep, parts, and assemble, and part and tools to torque, yes?

Have the heat exchangers tested for leaks and structural integrity. If at fault, either repair or replace as you wish or can.

Get new or bend and weld reinforcing steel matter to the radiator brackets. They suck and are weak. This is a known, so I've read, yet not too often.

Find machine shops through these resources in your area:
- https://www.brickboard.com/SHOPS/
- https://www.volvomechanics.com/
- http://www.cartalk.com/mechanics-files

On facebook, Try the Volvo 240 fan club for suggestions.

Again try http://forums.turbobricks.com/

No obvious signs of cylinder head seal loss and leaking there? Images may help of the cylinder head under side, the gasket, and the engine block top.

Does that help?
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Thank you for the reply! I've ordered the basics from eeuroparts. The exhaust manifold is out now, intake manifold is just about out.

260k miles roughly, the odometer broke 3+ years ago. The thing with the oil light, I noticed the wire is completely severed. I don't know how the light even goes on/off at all. It is in the block underneath the turbo, near the water pump. I think that's what it is. The wire is strung underneath the front of the engine. My next order, which is difficult, is to get all the oil crud off the engine block. It's a huge mess.

Hi walczyk,

Did you research the best gaskets and seals and such? I'm unsure what is best anymore.

Yep, if conductivity is lost between the oil pressure switch, the oil light stays on.

Yet your alternator is at the driver (car left side - intake port manifold side) at the top. I forget if A/C or the power steering pump is below right now (Ooooh, we have google images search - nope, no help).

If your engine is oil basted, part of the concern is to why, so, a check of the positive ventilation crankcase system. I'm unsure whether you have sieve. If use mineral, and don't change it, the PCV breather flame trap and the oil separator breather box gets coked up. One way to check is to disconnect the PCV pipe at the accordion style air intake pipe right before it secures to the throttle body. Blow through it with the oil fill cap off. Should be easy to exhale through. Restore and re-secure the fill cap, and so long as the oil drain plugs is in, it should be very hard to blow through it at all.

You may want to consider the OEM oil breather separator box and O-ring for replacement.

It can be very dangerous to let oil and oil collected grime form on the engine, more so on Turbos. Engine fire risk.

Cover up holes with plastic wrap and use some Gunk engine bright. Let sit. Hot water helps with a normal pressure hose spray nozzle.

Take a look at the harmonic balancer crank pulley. Check for cracks in the bushing material between the outer and center cast steel parts.

Else, well, I dunno. Motor mounts? Transmission mount? As your budget allows.

Seem like you have some work to do.

Wish I had a garage. I have a cylinder head gasket and one or more exhaust gaskets in need of replacement on the 1990 240 DL "li'l red" Wagon, with M47 II glass-geared transmission and all body panels in different red hues. Like to do so before it gets to a point what you are encountering. Oh well.
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I write:

"Yep, if conductivity is lost between the oil pressure switch, the oil light stays on."

No, incorrect, wrong, nope. Sorry.

The oil switch light, when encountering the rising oil pressure to the threshold, open the switch (circuit) and loses connection to ground, so the instrument cluster oil pressure light is off.

See: http://volvowiringdiagrams.com

940 Wiring Diagrams

Volvo 940 1993.pdf

PDF page 31 of 32.

D'oh!!!!


Also, you'll need to know how to flush the coolant-compromised transmission fluid in the transmission and throughout. Much fluid remains in the torque converter, yet as your pulling it all owt, should be easy.

You do not want any remaining coolant anywhere transmission fluid and engine oil should be.

Also, separating the transmission dipstick tube where it secures and seals at the transmission fluid pan can be a real (I'll be polite) bother. Be careful else you can screw stuff up. You'll need to drop the pan, inspect residues and hope for no chucks or heavy wet clutch disc grit.

I dunno whether your state, where ever you reside mandates emissions testing. Yet using the blue coolant (did you use a silicate-free coolant?) may mean the catytlit convertor should be okay.

Though when you get it back together, running and driving, check the OBD codes for engine control sensor and device faults.



Oooop. Ha-ha! I'm a dyslexic SOB. Yes, an SOB. Meet my mudder and you'll see!

SOB Boyeeeeeeeeeee

And now, time for something not so different:





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Sounds like a "bad" headgasket to me.

Pull your spark plugs. Do any of them look like they have been steam cleaned when compared to the others?

It's not a horrible job, but slightly more labor on a turbo car because more crap has to be removed.