'91 740 T head gasket

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Old 05-16-2018, 05:33 PM
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Unhappy '91 740 T head gasket

Hello,

On my way to work noticed some mist behind me. I thought it was me kicking up road dust from the 18 wheeler in front of me hauling grain. I was wrong. Pulled over and steam was coming from under the hood. I got her home (only a mile ). So it looks like the head gasket went? The leak appears to be coming from the intake side in the middle of the block. There were no signs of this about to happen, the car had been running fine. No coolant leaks and oil level is good. It still is running good, just a coolant leak!

So far I have researched that you don't have to disconnect all fuel injectors/plumbing etc from the intake, just disconnect the intake and lay off to the side.Disconnect the exhaust manifold/turbo.Might have some broken bolts here. Remove distributor, plgs, timing belt, cover and associated equipment. Make sure you have all timing belt marks lined up before removing (crank/cam). Get new head bolts and a water pump, plugs, t-stat, gasket set, timing belt.

Next once head is off check w/ straight edge for warpage, no more than .004" combined for the block and head. Clean off the block gasket surface and head surface of all material.

I don't know of how to check for cracks in the head, I don't have a dye penetrate kit or magafluxing capability.

Re-assemble and torque head bolts in direction and sequence as required, also remove head bolts in order per mfgr requirements.

Oil head bolts before install, no rtv on bolts or head gasket.

OK, my questions:

Should I bring the head in to a machine shop to check for cracks and or warpage?

Could this be anything else beside a head gasket? I have read about heater hoses near the fire wall but did not see any leakage there, just under the intake manifold runners in the middle of the block.

Car now has 166,000 and has been doing good. I had the heat to off when I started and turned to full on, just on the selector dial, from cold to hot. Did not have any heat when I noticed leak.

Any input appreciated,
Thanks,
Mike
 
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Old 05-16-2018, 07:30 PM
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Wipe it down and fill it with water and start it up. Look for the leak. Also check your oil to make sure there isn't water in it. Check the coolant bottle and make sure there is no oil or exhaust in it. Based on what you see then look at the repair.
 
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Old 05-16-2018, 11:30 PM
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re checking the head for cracks, you send it off to a machine shop, they plane it and pressure test it, only costs a couple $100.

I believe you can leave the exhaust manifold on the head, and just remove the turbo from the manifold... if you take the exhaust manifold off, odds are very good you'll need to replace several exhaust studs, and maybe even helicoil them.
 
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Old 05-16-2018, 11:32 PM
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oh, and for sure, while you're in there replace ALL the coolant hoses, including the heater hoses, and the oil cooler hoses, as those all get neglected, they are 25 years old, and its way due.
 
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Old 05-16-2018, 11:34 PM
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re the water pump, if you get an aftermarket pump, get the gasket kit FROM VOLVO. or just get a Volvo pump, it comes with the good gaskets. especially that top one that fits under the head overhang, ALL the aftermarket gaskets are crap and leak in no time.
 
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Old 05-17-2018, 11:09 AM
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Thanks for the input!

pierce that sounds like a good plan on the exhaust manifold. I am thinking there are three bolts on the turbo to the aft pipe. Sounds good on water pump, will get a Volvo unit. I will replace all hoses, I have been fixing dry rotted ones as I go but now I will do all of them.

jagtoes, I will do that to confirm location of problem.I did check oil yesterday after I got her home and no milkshake, just oil, so that was good to see. I will check the resivor as you mentioned. Probably going to get started on this Friday or Saturday.

Thanks again,
Mike
 
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Old 05-17-2018, 04:18 PM
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If you want to save some money and try a quick fix first, try adding some Blue Devil leak sealant. I had a Ford Taurus that developed an external(not between cylinders) leak like yours and was going to junk it rather than repair it. I threw in a bottle of that stuff and I've put over 20,000 miles on it with no leaks.
 
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Old 05-17-2018, 08:51 PM
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Unusual place for HG leak but you never know... If the engine was not overheated then the head should not be warped. New bolts are not necessary. I move the intake manifold to the right and tie it there for the duration. I take off the exh. manifold with the turbo, undo it from the bottom exh. pipe. Soak those exhaust nuts/studs with PB blaster for a couple of days prior to removal--breakage is common and PIA.
 
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Old 06-07-2018, 12:38 PM
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Well finally got a chance to work on it. Not a head gasket at all, ruptured heater hose. Under intake right near where the head and block mate. Hose runs from block to heater control valve. And is no longer available. Called FCP, IPDUSA and a dealer. All were very helpful. So 1' length of 5/8" hose and a gallon of antifreeze and I am back in business.
 
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Old 06-07-2018, 03:20 PM
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if that hose ruptured, I would suggest that you should, at your leisure, check the condition of the various coolant plumbing on the exhaust side of the engine, specifically, the coolant plumbing to the oil cooler and the turbo. while some of this is hard pipe, there's some rubber bits to it too, its hard to get to and often neglected. and its NOT something you'd want to have to fix on the side of the road.
 
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Old 06-08-2018, 09:43 AM
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Will do pierce. It is almost oil change time so I will check it out. I would assume the oil cooler is mounted to the radiator or near it?
 
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Old 06-08-2018, 02:05 PM
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no, the oil cooler I'm talking about is the thing the oil filter screws onto thats on the exhaust side of the block and behind/below the turbo.
 
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Old 06-08-2018, 11:58 PM
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The '91 should have an external oil cooler indeed mounted under the radiator. The later set up has the rubber coolant hoses by the oil filter...
 
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Old 06-09-2018, 05:53 AM
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yeah, I'm talking about the cooler the oil filter is screwed into on the turbos...
 
Attached Thumbnails '91 740 T head gasket-adaptor%5B1%5D.jpg  
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Old 06-11-2018, 10:36 AM
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pierce, am I looking at the lines coming off in front, right under the turbo? There appear to be two rubber lines there. The area where I think the oil filter is looks to have hard lines and a oil line crossing over it from the turbo to the block.
 
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Old 06-11-2018, 02:45 PM
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ok, good if you have hard pipes on the oil filter cooler, i've seen rubber lines used there.

the turbo has 4 lines connecting to its mid section bearing... 2 are oil, and 2 are coolant. the oil ones are directly across from each other, as are the coolant ones. the pipe that goes down at an angle from the turbo and sticks into the bottom of the engine block is definitely oil, thats the oil return line to the pan, this is clearly visible in that picture I posted.... so the two banjo fittings at 90 degrees to that oil return line, THOSE are the turbo coolant lines...
 
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Old 06-11-2018, 03:11 PM
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OK, I will check it out. I have not looked at my car yet, just looking at the pic you posted. Thanks for all the info.
 
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