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940 - Chasing Coolant Leaks

I always scrub the block surface with a piece of 3M red Scotch Brite and a little solvent by hand. Don't use those Roll Lock discs on an air tool. They can remove metal rather rapidly.

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I did check and they were dry, but old, so I replaced the heater hoses as well as the heater valve. It was still dry before I started down this HG road.

The leak is coming from the exhaust side, I thought it might have been the coolant hard line or its heater hose connection above the bellhousing, but every time I felt it, it was always dry. The only place with a leak potential that is above the block heater is the HG as far as I can tell.

There is also the O-ring at the water pump end of the hard pipe. When I replaced my pump (possibly OEM) I found that O-ring to basically have turned into a crumbly rock. Leaks can also run along the hardline and show up in weird places.
 
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cleaned both surfaces with some brake cleaner sprayed onto a scotchbrite pad (cant buy red 3M unless I have a pro license or something)

Cleaned up pretty nice!

I installed the intermediate shaft seal again after messing up the first one.

I then used the special tool to install the crank seal. The outer lip of the innner ring was all messed up after I installed it but I was able to gently poke it in with a screwdriver. The inner lip of the inner ring should have been placed properly thanks to the tool. Fingers crossed there are no leaks.

Will be bolting the water pump to the block (without tightening it up) before replacing the HG and the head.
 
Looks good. How straight is the head? Warp in both directions?

Thanks, I laid the straightest edge I could find across the head in all directions, and could only see the faintest sliver of a sliver of light, if anything at all. I did the same thing with the block, although it was a lot harder to check.

I was able to get the block heater to rotate in the hole with some hammer smacks, but have not been able to get it out yet. I would like to get that out before I put the head on, as the extra space gives more leverage. I sprayed a bit of PB around the edges to hopefully help.
 
Thanks, I laid the straightest edge I could find across the head in all directions, and could only see the faintest sliver of a sliver of light, if anything at all. I did the same thing with the block, although it was a lot harder to check.

What's "the straightest edge you could find"? Metal ruler? Professional machinist's edge? Something in between, most likely?

As well as shining a light from behind, you can put the straightedge down on top of a feeler gauge and tug gently. Gauge pulls out with little or no friction = gap larger than the gauge.
 
99.9% chance the block is perfectly straight. If you don't see any heavily corroded spots, it should be fine. If you don't have a machinist straight edge, just take your head to a shop and have it checked. Leave it with them to fly cut if is is more that .008" warped. I rarely see a redblock head that is straight unless it just came from the machine shop. Almost all of them are slightly warped.
 
What's "the straightest edge you could find"? Metal ruler? Professional machinist's edge? Something in between, most likely?

Something in between, but I guess that's not the right way to do it.

99.9% chance the block is perfectly straight. If you don't see any heavily corroded spots, it should be fine. If you don't have a machinist straight edge, just take your head to a shop and have it checked. Leave it with them to fly cut if is is more that .008" warped. I rarely see a redblock head that is straight unless it just came from the machine shop. Almost all of them are slightly warped.


I'm asking my local Volvo group for a recommendation on where to take the head. I have a guy who does machine work but I don't know if he has the equipment to resurface such a large surface.

Thanks!
 
Something in between, but I guess that's not the right way to do it.

Well, depends on your risk tolerance and what you know about your straightedge. It's entirely possible that you have an edge that's straight within 0.001 but there's no good way to tell without checking against known quantities (another good edge, machinist's tools, etc). It's also possible that an only-sorta-flat head will work fine for many years. Given the hassle involved with the job it seems worth checking.

That said... if you want to DIY and have the tool on hand for future use, a decent hobbyist grade straightedge is <$30 on Amazon.
 
Scothbrite? no, no, no. The internet is littered with stories where scotchbrite was used. It contains aluminum oxide particles the spell death to an engine.

WELL ****. Looks like I just destroyed the engine if the internet is to be believed....

Edit: Yup it really looks like I screwed up here. I used it on the head and the block. FML.
 
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It's not over unless you rotated the engine with the aluminum oxide particles on it. The internet also says there's no reason you can't clean it off. Unfortunately, you'll have to remove the oil pan to make sure all of it is gone. I don't know how that would work with the head off the block. You might be able to get away with just cleaning the surfaces and bores if you dump some oil through the system before filling.
Do a web search and look at a few posts. I can't suggest anything because I haven't had to deal with this yet, but some suggest that the main problem with using scotchbrite and similar abrasives is lack of cleaning afterwards. Maybe try pulling as much off as you can with a straw duct taped to a shop vac before doing anything like dabbing or wiping. Both on the surfaces and in the ports. But you should read as many articles and forum posts on cleaning off scotchbrite as you can first, since it's a bit of a delicate situation now.
The aluminum oxide can embed in aluminum, and in the head surface it probably already has. If you haven't been to a machine shop yet for the the head, this would be a good time. Just warn them that you scotchbrited it before they go to work on it. I hope you didn't scrub the piston crowns with the stuff. If you didn't, and you get the rest of it off, you might be fine.
I would call this an example of why you need to read extensively about anything you're going to scrape or spray on internal machine surfaces before you do it, but this is a bad example. Too many people will tell you with a straight face that scotchbrite is a good solution.
 
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I'm confused, I am looking more into it and I see that red 3M pads that were recommended, also apparently have aluminum oxide in them.

3M Pad website

This basically seems like I am f***ing toast. I am reading articles about people who are suggesting nitric acid....dumping gallons of kerosene or gasoline in the engine and not having it work.... Here I was hoping last night that I would just be able to swab the oil passages with Q-Tips and brake cleaner.. I guess that won't work.

I will be bringing my head to a head shop that I found. They will be cleaning the head in addition to resurfacing. So at least that part will be taken care of.

For the block, the Head guy recommended I use sandpaper and a wood block...I assume this time after I plug the oil passages, which I didn't do when using scotchbrite. He said I will need to 'drop the pan to flush the water jackets'.

I will need to figure out how to drop the pan. Preferably without the head attached, but I don't know how possible that is. Don't I need to lift the engine to drop the subframe + oil pan?

Is now a good time to mention that I also used scotchbrite to clean the aux and crank shafts? Just briefly, and I cleaned those shafts off with compressed air.


I swear that after I end up basically doing a ENGINE REBUILD the coolant leak better not still be there.

I bought a 0km B230F last week, coincidentally. I didn't think I might actually need it so soon...


It's going to be a while until I can get the head back on the block. Is the block going to rust over? How do I prevent that while also not further screwing up the block?
 
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I only see the one forum post from a guy who used scotch-brite and had a later engine failure. While it's worrying, one failure does not an example make... I wouldn't panic just yet.

- You didn't use an abrasive disc on a power tool like the GM bulletin warns about.
- You used them wet with brake cleaner which will help pick up any stray particles.
- You can easily wash down exposed surfaces and passages at this point to further collect particles.
- You're gonna change the oil anyway to get rid of any solvents or crap that fell down the passages. If especially worried you can do it twice - once before and once after first run... Oil filter catches down to 30 microns or so which is the expected size of 600 grit green scotch-brite.
- 2manyturbos, who does this for a living, routinely uses the more aggressive red scotch-brite and has not reported problems.

I would wait for his expert opinion, of course, but seems like you'll most likely be OK...

It's going to be a while until I can get the head back on the block. Is the block going to rust over? How do I prevent that while also not further screwing up the block?

A layer of oil or light grease will keep moisture out. Preferably something not super thin so it stays on there. Wash off before installing.
 
I'm confused, I am looking more into it and I see that red 3M pads that were recommended, also apparently have aluminum oxide in them.

3M Pad website

This basically seems like I am f***ing toast. I am reading articles about people who are suggesting nitric acid....dumping gallons of kerosene or gasoline in the engine and not having it work.... Here I was hoping last night that I would just be able to swab the oil passages with Q-Tips and brake cleaner.. I guess that won't work.

I will be bringing my head to a head shop that I found. They will be cleaning the head in addition to resurfacing. So at least that part will be taken care of.

For the block, the Head guy recommended I use sandpaper and a wood block...I assume this time after I plug the oil passages, which I didn't do when using scotchbrite. He said I will need to 'drop the pan to flush the water jackets'.

I will need to figure out how to drop the pan. Preferably without the head attached, but I don't know how possible that is. Don't I need to lift the engine to drop the subframe + oil pan?

Is now a good time to mention that I also used scotchbrite to clean the aux and crank shafts? Just briefly, and I cleaned those shafts off with compressed air.


I swear that after I end up basically doing a ENGINE REBUILD the coolant leak better not still be there.

I bought a 0km B230F last week, coincidentally. I didn't think I might actually need it so soon...


It's going to be a while until I can get the head back on the block. Is the block going to rust over? How do I prevent that while also not further screwing up the block?


Don't worry about some moron posting on the internet. I have been using red scotch brite pads to clean engine parts for the past 25 years. I wouldn't want to fill the crank case with scotch brite pads and run the engine. That would be my only concern. The crank shaft shop in Albany used a belt to polish the crank shaft journals after a crank grind that was basically a long strip of scotch brite with a backing material. Don't overthink this. Any time you pull out a piece of emery cloth, sand paper, etc you are using aluminum oxide.

You are so hosed. Even the cylinder hones used to finish off a re-bore job for new pistons contain aluminum oxide. Better throw all the engines in the world into the scrap pile. They were ruined before they were even assembled.

https://regismanufacturing.com/aluminum-oxide-cylinder-hone-stone-sn-300ax/

BTW, I just run over the block surface with a shop vac to clean up any carbon, rust and gasket particles that cleaning knocks loose. As said above, you are going to change your oil again once you run the engine. The filter picks up anything you missed or couldn't get to.
 
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Once this is all put back together and it starts and runs, I am going to be very relieved. Until then, I definitely feel that I have gotten in way over my head trying to fix a coolant leak. I am the kind of person that needs to learn by doing, and this is clearly the first time I have done anything like this. Next time will be easier.

Don't worry about some moron posting on the internet. I have been using red scotch brite pads to clean engine parts for the past 25 years. I wouldn't want to fill the crank case with scotch brite pads and run the engine. That would be my only concern. The crank shaft shop in Albany used a belt to polish the crank shaft journals after a crank grind that was basically a long strip of scotch brite with a backing material. Don't overthink this. Any time you pull out a piece of emery cloth, sand paper, etc you are using aluminum oxide.

BTW, I just run over the block surface with a shop vac to clean up any carbon, rust and gasket particles that cleaning knocks loose. As said above, you are going to change your oil again once you run the engine. The filter picks up anything you missed or couldn't get to.

I know that you are very experienced and I trust your knowledge of these engines and these procedures more than I trust the random guys on other, non-Volvo forums. It's just that I found several postings with anecdotes about engines ruined by the aluminum oxide so it definitely caused me some concern. If you don't think it is bad at all then that is very relieving, and I believe it. I don't know enough about it myself to form my own opinion.

My apologies for being redundant, but I really want to make sure I understand this process;

-don't need to drop oil pan
-vacuum top of block
-wipe top of block down with some solvent and then cover with a thin layer of oil to prevent rust while head is at the shop.
-assemble engine and run with fresh oil for only a very short time. (I have read anywhere between 15 minutes and 100 miles)
-change oil, then change again after another 100-200 miles.

-should I attempt to swab any oil passages with solvent and Q-tip or is that just a dumb idea? Is non-chlorinated brake cleaner okay (as a solvent for this job) when sprayed on a paper towel, or should I go buy carb/injector cleaner?

I thank you all very much for all your help, I really couldn't do this without it!
 
You summed it up quite well. I wouldn't worry about using a Q-tip to clean the passages. Brake cleaner is fine. It pretty much evaporates leaving nothing behind. You are doing fine. It's best to ask questions ahead of time. Don't leave things to chance. You are being meticulous, the same way I work on these engines and basically, anything I touch. Do it right, do it once. The oil passages that are feeding the top end can be cleaned with paper towel to soak up oil and residue, then, spray some solvent on them and do the same. Wick any suspect material out of them. I use engine cleaning solvent for all of this. It may not be readily available where you are at. The same solvent that goes in a parts cleaning solvent tank. It is non-flamable, therefore, you can safely vacuum it up with your shop vacuum. That's how I clean out all the head bolt holes and the oil passages. I just use a trigger pump spray bottle to spray the solvent.
 
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Got my head back from the shop. They only took .005" off but I needed the head cleaned anyways after using the scotchbrite so the $95 CAD was worth it to me. They also offered to vacuum test the valves but I didn't really have the extra $90 to spare, so I opted for just the resurfacing and washing.

I should have removed the valve hushers before the wash though, as when I removed them there were some rubber bits left. I cleaned them the best I could.

I will install the head onto the block, then put the camshaft in, using the existing caps and shims, but no valve hushers. Then I will re-do the shims. Then I will remove the camshaft, install the valve hushers, re-install the camshaft, and then put everything else back together. (I know some people don't use hushers, but I have 2 sets of new ones so I figured I might as well.)

I finally got the block heater out. I had a bit of help, but between a chisel and a pair of vice grips we were able to knock and wiggle it out. I cleaned the hole with a razor as there was some rubber bits. I covered the surface of that hole in oil so it wouldnt rust. I'll clean the oil off before installing the frost plug tomorrow. It's a 40mm cup style plug. I'll be using dry ice to shrink it before installing, and Permatex aviation gasket to help seal it.
 
Five thousandths is pretty close to the warp limit for that head, so you bought yourself a lot more time before you have to do this again.
 
Well, this new frost plug isn't going in.

I've spent $50 on two batches of dry ice so far.

I've cleaned the plug hole very well using a razor and a bit of sandpaper.

I've heated the plug hole with a blowtorch.

It certainly isn't "sliding in" as a previous tb post mentioned. It's not even smacking in with a socket and hammer. It's a 40mm plug that I found among a pile of parts that I bought from a Volvo mechanic. It is not an OE plug but it was filed under the OE part number. It's the cup style.


So, given that I can't get the damn thing in, I'm resorting to buying a new block heater that I will never use. I will try to get a Dorman rubber expansion plug first, as they're about 1/5 the price.
 
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