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-   -   Oily sludge and its eventual destruction (a work in progress) (http://d24t.com/showthread.php?t=809)

jbg 04-13-2012 02:57 PM

My engine is an oily mess (a work in progress)
Hello everyone,

When I bought my D24T-powered 740 back in 2007 it had a noticeable oil leak. I figured "hey, it's an old car, and I'll just fix it, no problem". I actually posted this type of message on the "volvo_diesels" mailing list around the same time. Fast forward to now and the leak is much worse. It will leak about a quart of oil in 750 or so miles. The jet black markings of my car are well represented in both my work's parking lot, and my home turf.

I cannot determine the exact source of the leak. It is built up on the oil pan, turbo, turbo intake tract, oil cooler, near the front of the engine at the crank, etc. My plan is to degrease and entire area, hose it down, and see if I can figure out where the oil is coming from. If I cannot, I'll clean it again and add some oil dye, and repeat.

My front suspension is in dire need of a rebuild but I'd rather not begin this job until that area is not a greasy, sticky, horrid mess! I'll update this thread with pictures and information as I tackle the clean up and investigation.

It begins tomorrow! :eek:

jbg 04-14-2012 11:23 AM

Update #1:

I de-greased the front bottom half of the engine as this was the worst or it. A significant collection of oily grime was on the bottom half of the alternator, front of the sump, oil filter, and where the oil pump and engine block meet. The oil cooler and its two coolant lines were free of oil. Looking at my VADIS diagrams I see there is an oil pump gasket (p/n 3507028) and naturally the oil pan gasket as plausible culprits.

There is a thick and sticky coating of oil on the front of the cross member. I suppose this is due to the oil leaking at speed and splashing on the cross member as it travels rearward.

I have a few questions based on my limited research and what I've been able to see on the car:
  1. Are the seals used on the timing belt cover only used to keep debris out of the belt?
  2. Are there any additional paths where oil can escape on the front of the engine? I'm ruling the head gasket out as the engine is dry at that level.
  3. Is there a front crankshaft seal? My VADIS does not show one, and Rock Auto seems vague.

Here is a pic of after the initial clean up:


Jason 04-14-2012 01:28 PM

There is a front crankshaft seal that the pulley rides on which could be leaking, also the oil pump gasket at the block could be leaking as well. I have seen the oil cooler o-rings petrified on a few different vw diesels, so they are suspect, as is the seal at the block where the oil filter/cooler adapter assembly bolts on. The rubber seal on the cover is pretty much a dust cover, or to keep it from being metal on metal and rattling and making noise I suspect. Your picture also shows the compressor housing of the turbo being oily, which can be from crank case blow by oil draining into the intake tract and leaking out where the intake neck attaches to the turbo, though I doubt your loosing much oil there. It sounds like you should be able to start it up and see a rather aparent leak at the amount of oil your loosing.


v8volvo 04-16-2012 09:00 AM

Glad to hear you are going to tackle it! You and the car will both be glad you did. :-)

As you have already found, diagnosing oil leaks in this area can be tricky since the mess goes everywhere as soon as the car gets driven. As Jason suggested, start with the easy and obvious... don't assume it is a front crank seal or oil pump gasket leak unless you can see the leakage obviously coming from there. Oil cooler seals can leak, the turbo inlet can drip large amounts of oil from the CCV system or have leaks from the oil supply/return lines, a common valve cover gasket leak can come all the way down and simulate leakage from a different area.... etc.

One suggestion: due to the exposure of this area of the engine to wind from the radiator fan and/or airflow around the car at speed, rather than cleaning the area and then driving the car to see where the leak is coming from, you may have better results from cleaning it and then running the engine with the car stationary as far as pinpointing the leak source. If you have a weekend day free, you can idle the motor for several hours or all day if necessary. (If your car is an automatic, though, be sure to do this with the transmission in 1st gear and the rear wheels off the ground on jack stands -- idling for very long periods in neutral can cook an otherwise healthy ZF trans, and idling in gear for very prolonged periods can lead to overheating of the trans fluid.)

Hope you are able to figure it out! One other thing to look at -- take the upper timing belt cover loose and look inside for evidence of oil leakage. If the leak is coming from the front main seal, you will also see oil everywhere inside the belt cover -- the TB acts like a conveyor belt and flings the oil all over the place. If it is dry in there (and you hope it is), then the crank and cam seals are fine. If it is not dry, then you have found your issue, and you do not want to even crank the engine again until you have fixed it... oil contamination weakens timing belts, and if that belt breaks, your engine is hosed!

jbg 09-03-2012 06:22 PM

Thank you for the responses to my oil-related ailments. I apologize for the prolonged radio silence but life gets in the way of our hobbies sometimes. The Volvo has been sitting so long the battery has lost its charge. I'm going to de-grease once more and check behind the front timing belt cover for oil. If this area is dry I'll charge the battery, start the engine, and play the waiting game. It is an auto so I will take your advice v8volvo and put the rear on jack stands.

Ideally I'd like to get this sorted before winter rolls in. I've lost a good amount of time but if I'm lucky I should be able to make some progress.

jbg 08-02-2013 12:59 PM

And we're off!
If you're also a reader of the D24 Mailing List you might recall the tale of a D24T owner who's oil cooler went bad and introduced oil into the coolant, and coolant into the oil. This prompted a multi-day conversation on the proper non-sudsing soap to use. I am that owner, and now I'm able to start to remedy the situation.

Today I drained the oil and coolant. The coolant was about 75% green coolant and 25% oil. I couldn't find a petcock valve on the radiator so I removed the lower radiator hose. Per the advice of E C Yarter on the D24 ML I purchased an "oil filter adapter" from eBay to replace the oil cooler. This adapter has 3 threaded 1/8 NPT bungs to screw in plugs, temperature senders, pressure senders, etc. I have a VDO oil temperature sender in one and the other two holes are taped and plugs inserted. The adapter comes with a 3/4-16 male-to-female threaded fitting. I also purchased an OEM D24 double-male oil filter nipple (PN 1257040). Assembly goes as follows:

Oil mount -> double male nipple -> oil filter adapter -> 3/4-16 threaded fitting -> oil filter.

I think it'll work out pretty well and I can monitor the temps now that the cooler is gone. Tomorrow I'll install the adapter and associated items, and a new filter. Once we're buttoned up I'll fill with new oil in the engine and 1 cap full of washing powder and water into the overflow reservoir. According to some folks on the ML this could take 8-10 times of filling, rinsing, draining; ugh.

I do have a question: is the lower radiator hose available in the US? I see on RockAuto they list "ÜRO PARTS Part # 1257992" for $12.76 ... but those European-sourced parts can be awful pricey to ship. :eek:

I'm also going to head to the home store and source some brass plumbing plugs. These are for the coolant hoses I won't be needing with the removal of the oil cooler. Yippie!

casioqv 08-03-2013 05:24 AM

Good luck with your cleaning process! After the cleaning is a good time for all new hoses and a new radiator, especially if you were planning to do it anyway. I'm not sure about hose availability.

Do you have a link to that oil adapter? I really like that idea as a way to add an oil temp gauge to a D24. If you saw my thread on the giant oil cooler I added, I'm now slightly concerned that I'll be over-cooling my oil as the thermostat I used doesn't fully block off flow to the external cooler.

jbg 08-03-2013 06:00 AM


Originally Posted by casioqv (Post 7231)
Good luck with your cleaning process! After the cleaning is a good time for all new hoses and a new radiator, especially if you were planning to do it anyway. I'm not sure about hose availability.

Hi Tyler,

Yes I was planning on buying one of those Nissens radiators off eBay as discussed in this forum. I'll need to investigate the hosts in general and check their availability. Perhaps a separate thread is best for this. I'm sure all of the hoses are in need of replacement anyway.


Originally Posted by casioqv (Post 7231)
Do you have a link to that oil adapter? I really like that idea as a way to add an oil temp gauge to a D24. If you saw my thread on the giant oil cooler I added, I'm now slightly concerned that I'll be over-cooling my oil as the thermostat I used doesn't fully block off flow to the external cooler.

Here is a link to the exact same product and seller I bought mine from:


I needed to debur a few of the internal surfaces of that adapter with a small file. Otherwise it performs as advertised. As mentioned before I opted to buy the D24 double-male oil filter nipple as opposed to cutting the D24T threaded nipple used with the oil cooler. Using the D24 nipple with the adapter's threaded male-female adapter gives a very secure fitting without the need of the OE nipple's nut or using something like Locktite. I'm not sure if I'm describing that well enough. :D

jbg 08-03-2013 12:34 PM

More removal ...
I finally removed the oil cooler and the threaded "oil pipe" from the engine. I'm glad to have these items gone. I still need to fully remove the two coolant hoses formerly connected to the oil cooler. A trip to the home store for a few brass plumbing plugs seems to be the agreed on method on plugging up the now exposed coolant circuit.

I did note that the large o-ring from behind the oil cooler looked a bit brittle. It was still rubbery, but it did look to be old and perhaps capable of leaking oil at a high-rate of PSI; interesting. :confused:

I have the OEM double-male nipple, the adapter's male-female threaded nipple, and finally the oil adapter installed. The adapter is so shiny and the VDO temperature sender is too very shiny. Those pieces really illustrate the horrific oily mess that the front passenger-side quadrant of the engine really is. I'll update this thread with some pictures soon.

Update: with the oil adapter's threaded nipple screwed fully into the engine the oil adapter itself it loose enough to turn with your hand. So it seems as though I need some type of a shim to push the adapter further down on the engine so tightening the adapter fitting seals the adapter to the engine. This ought to be interesting.

jbg 08-06-2013 04:18 PM

A big thanks to Anders for his help in providing a part number to a much needed freeze plug!

The last few days have been very productive for the Volvo. I have removed the oil cooler and its associated plumbing. I decided to skip the installation of the oil adapter as the car was parked on a public street and the neighborhood "passive-aggressives" were in force. Instead I installed the new OEM double-male oil filter nipple with blue Loctite on its threads and a new Wix oil filter (sans Loctite!).

The oil cooler hose that plugs into the block at the thermostat housing was a real bear to tackle. I tried tapping the hose barb out of the block with a punch, but as the engine is installed in the car this proved very tedious. Instead I took the low road of cutting the barb with a cut-off wheel and sawing and punching until the barb could take no more. I even managed to spare the block any damage, hizzah! I installed a Dorman (PN 555-016) freeze plug at 23.90mm width with red Loctite.

At this point I still need to address the coolant barb at the rear of the cylinder head. A freeze plug would be ideal but it's too cramped back there. Instead I'll use a hose plug and (hopefully) call it good. At this point the engine is ready to receive its fluids and multiple applications of the cooling system flush regime.

Question: I removed the thermostat as it was (probably) in need of replacement. I planned on keeping it out for the duration of the flushing. My logic was no thermostat would provide better soapy water flow; thoughts?

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