Member Since: 07 Oct 2011
Location: Oslo
Posts: 61
Backyard body off - low oil pressure after rebuild
Always wanted to do a body off - for the experience. Bought a Discovery 3 where the water housing had split, most coolant was gone in a few secs and subsequent blown head gaskets as the result. First some photo's of the "rig" I used. Job lifting the body was done with 2 jacks, one on each side.
Lifted the body just high enough to roll the chassis forward.
Piston #3 damaged/melted.
Engine rebuild in progress with a second engine block that followed with the D3. OEM FoMoCo oil pump in place.
Reconditioned turbo and HPFP installed with all new injectors and glow plugs.
Back in chassis, autobox and new crossover pipe in place.
Rust from chassis removed and treated in bitumen-based coating.
Used 3 months to do the job, mostly evenings after work and weekends. Watched the excellent videos from Piston Broke Garage and LRTime together with Topix' workshop manual to do the engine re-assembly. With the car followed a complete second engine. Used the engine block from engine #2 which was in good shape. According to the previous owner it was "in a excellent condition". Checked block and cylinder heads for warping, and calculated correct thickness of head gaskets to be 2 notches. Rebuild cylinder heads with 24 new hydraulic valve rockers and new cam chains. Pre-oiled the oil pump and galeries. All bolts tightened according to the correct sequence and torque specs.
Used 12 mm threaded rods on the corners to guide the body correctly down on the chassis. After all connectors were back in place (you always forget some) it took various attempts before the engine started. However the oil light remains on. On slight revving the light goes out. It remains difficult to start the engine. When it runs it sounds totally nomal. No visible leaks or anomalies.
The burning question now is.... why the difficult start and low oil pressure? Removed oil filter which was soaked in clean engine oil, and oil drained away after pulling out the filter. I will get a compression test kit and check the compression of each cylinder. I probably should at least have replaced the piston rings, and grinded the valves and valve seats, but since everything took a lot more time than anticipated I did not. But if the compression is good on all 6, what else could it be? Does the new oil pump need better priming?
Last edited by dutchviking on 30th Aug 2023 6:42 am. Edited 1 time in total
23rd Jul 2023 2:27 pm
Windsurfnut
Member Since: 18 Nov 2022
Location: Cognac
Posts: 11
Fair play to you for taking on this repair. Pretty gnarly lifting the body off like that. if you have watched LR time videos I think you will find that he paid particular attention to looking after the cylinder bores. I don't think it is good to have them open and exposed to the elements to the point where they have rusted. Did you check/ replace the glow plugs while you had the heads off.
31st Jul 2023 4:25 pm
dutchviking
Member Since: 07 Oct 2011
Location: Oslo
Posts: 61
I put in new glow plugs all round.
I put the pistons at their lowest positions and cleaned each cylinder bore.
Since oil is flowing but does not build up pressure I think either the crank main bearings are worn or an obstruction somewhere in te bock prevents proper flow to the cylinder heads.
17th Aug 2023 11:02 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10674
Maybe crank bearing installed incorrectly with a hole blocked up not allowing flow?
Watch the lrtime Germans on YouTube. They will tell you how to rebuild.
Watch and see if you misssed anything important.
17th Aug 2023 5:52 pm
dutchviking
Member Since: 07 Oct 2011
Location: Oslo
Posts: 61
If these bearings are installed incorrectly then the previous owner must have that on his tab. And in my ignorance I never checked
17th Aug 2023 7:14 pm
Russell
Member Since: 23 Aug 2007
Location: Kent
Posts: 10564
Can you not get a pressure gauge and check the oil pressure. Have heard of people having issues with the pressure switch or wiringMY17 D5 1st Edition Namib Orange
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18th Aug 2023 9:44 pm
dutchviking
Member Since: 07 Oct 2011
Location: Oslo
Posts: 61
I tried with a pressure gauge but the needle is not even moving. I also tried the gauge on my own D3 where pressures were correct. I tried with 2 new, original oil pumps, but that doesn't help. It seems oil pressure is lost between the filter and the sensor. Might as Pete suggests be an internal leakage, like at the big ends or main bearings.
Last edited by dutchviking on 30th Aug 2023 6:47 am. Edited 1 time in total
21st Aug 2023 1:08 pm
LittleG
Member Since: 21 Sep 2013
Location: Wombourne
Posts: 392
Could it be debris in the oil pickup? Not too bad a job taking off the sump to check.
21st Aug 2023 5:36 pm
dutchviking
Member Since: 07 Oct 2011
Location: Oslo
Posts: 61
I removed the sump and the pickup but everything is nice and clean.
30th Aug 2023 6:44 am
sarumlight
Member Since: 06 Nov 2008
Location: Off the Plain
Posts: 1592
Is there a pressure relief valve on the pump that could be stuck open?
30th Aug 2023 7:08 am
wynanddb
Member Since: 22 Apr 2022
Location: Cape Town
Posts: 20
Any oil in the coolant (although might not have made it to there yet if). I had low oil pressure from a failed oil cooler gasket - not between the engine and cooler but inside the cooler.
3rd Sep 2023 7:00 am
dutchviking
Member Since: 07 Oct 2011
Location: Oslo
Posts: 61
I had a chat with Pistonbroke garage' Steve and he suggested to replace the oil cooler. Since I dis take the original one apart I replaced it with a new one but it did not help.
3rd Sep 2023 2:30 pm
wynanddb
Member Since: 22 Apr 2022
Location: Cape Town
Posts: 20
You will find it. With my starting issue I am also down to checking everything one by one.
Maybe have a look at a diagram with all the oil galleries and anything that could either obstruct or if left out could have a drop in pressure.
Might be difficult to see without a scope, but maybe you check if you can see if the 3 piston squirters are still in position for example.
If everything checks out, in the end I think you might have to check the big ends and mains - too much wear there or a spun bearing could have quite an effect.
3rd Sep 2023 4:31 pm
wynanddb
Member Since: 22 Apr 2022
Location: Cape Town
Posts: 20
Re: Backyard body off - low oil pressure after rebuild
dutchviking wrote:
Always wanted to do a body off - for the experience. Bought a Discovery 3 where the water housing had split, most coolant was gone in a few secs and subsequent blown head gaskets as the result. First some photo's of the "rig" I used. Job lifting the body was done with 2 jacks, one on each side.
How long did it take to get the body off if you have to hazard a guess? I might have to take my engine out again and was wondering about using your method.
4th Sep 2023 6:49 am
dutchviking
Member Since: 07 Oct 2011
Location: Oslo
Posts: 61
At first I thought it would take a day. But getting at the hight of 2 construction blocks the body slid off the jack. It does weigh a lot and has some momentum once moving. Nobody got hurt, but the lesson was learned and I attached 2 straps at the rear end to prevent side movements.
From this moment on I was more careful and only raised about 5 cm / 2 inches a time using wood blocks.
In the end doing this every evening after work it took one weekend and 5 evenings from starting to obtaining enough clearance to roll the chasis forward.
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