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Discussion Starter #1
Greetings All,

I was told by a mechanic that my SD33 non-turbo in my MQ is back-pressuring.

I no not entirely sure what that means, but exhaust gasses are coming through the oil filer cap when open, the dipstick tube when the stick is removed and the breather on the engine block, just behind the front left wheel

so I figure that the piston rings are worn and exhaust gasses are entering the crankshaft area as well as the top of the head where the camshaft is

the engine is under-powered, but working

I am trying to evaluate what my repair options are:

do I need to buy the entire rebuild kit? i.e the ones with all teh gaskets and pistons

the vehicle is a weekend runner only as is parked most of the time.

I will be weighing the SD33 rebuild cost vs engine swap cost.

the sd33 is an old engine and hp figures would be lower than a newer model diesel engine (e.g TD27, RD28). We don't get RD30 locally so its not an option). Tthen I would have to do a 24-12V conversion

so I dont want to spend the same (or close) amount of $ to rebuild teh sd33 when a more powerful, newer diesel engine would cost the same

as much as I would like to keep her original, if a different engine configuration means more power, more reliability, easier maintenance, then I would go that route

I have also seen a couple Chev 350 powered Patrols that are impressive, but I figure that those conversions would be costly and more complicated

I rather invest $ in some diff lockers and a winch, so engine rebuild cost isn't looking well for my pockets, since locker and a winch don't help out offroad if the engine wont take the truck there

I would really rather repair teh sd33, but need some options, that engine is pretty low power right now
 

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I wouldn't worry if it's not consuming huge amounts of engine oil.
Best you can do is upgrading to SD33T. No modern engine will be so bulletproof and reliable.
 

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blow back

When I had put a big snorkel kit on mine, I had the same trouble . I put a 2 breathers on the motor one in the oil cap drilled it out and ran a breather hose on it and ran it around the air cleaner with a small filter in the end. And a PCV (positive crankcase ventilation valve ) at the back of the valve cover , Also I pulled the vent tube of the side of the block, it was choked with oil and carbon. filled with petrol to burn the crap out pulled steel wool back thru it till it was clean So a couple of idea's. I stop using oil ...but I also stop using synsentic oil.
it get's to froffie. I went to kenworth trucks service Centre and got a real oil. now no problems it was driving me nuts but does leak or use a drop now, Cheers All :D
 

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Discussion Starter #4
Azotek

I agree totally, I really don't wanna change the old bulletproof engine. its not loosing a huge amount of oil, but is loosing power

mightydato

thank you for that reply, I'll look at some more venting options, like you described, really brilliant there, I hadn't thought of that

I'll look at cleaning out the vent tube on the block

And a PCV (positive crankcase ventilation valve ) at the back of the valve cover
where exactly did u install that at the back of the valve cover?

the power loss is bothering me when I go offroad as I pretty much got run her in 1st gear for inclines that should be approached in 2nd gear

rebuild kit is TT$5395\AUS$1140, which I rather not\cannot spend
 

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I put one vent hose in the back of the valve cover with the pcv valve and rubber bung, I put grease on the end of the drill bit to catch filing or shave cream and the other vent hose in tru the middle oil cap .. if your still running cast iron exhaust you will amazed how much grunt you get from a decent set of extractors and a big bore exhaust 3" And A American thunder big-block v8 muffler .
I can go hills now.

I found the butterfly plate was seized ,it robs heaps power of top of the crap exhaust manifold
 

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power loss

I put one vent hose in the back of the valve cover with the pcv valve and rubber bung, I put grease on the end of the drill bit to catch filing or shave cream and the other vent hose in tru the middle oil cap .. if your still running cast iron exhaust you will amazed how much grunt you get from a decent set of extractors and a big bore exhaust 3" And A American thunder big-block v8 muffler .
I can go hills now.

I found the butterfly plate was seized ,it robs heaps power of top of the crap exhaust manifold
Also as the saw other note, replace all fuel filters they has hidden little brass ones,
and give a bucket load of fuel injector cleaner ... see how Then check your exhaust system for shagged manifold crushed pipes and clogged muffler I have plenty of these motors do 800,000 + the injector pump is what kills them, if you get water in fuel ..
with 2 tanks I have 4 filters..
 

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PCV valve instalation

I put one vent hose in the back of the valve cover with the pcv valve and rubber bung, I put grease on the end of the drill bit to catch filing or shave cream and the other vent hose in tru the middle oil cap .. if your still running cast iron exhaust you will amazed how much grunt you get from a decent set of extractors and a big bore exhaust 3" And A American thunder big-block v8 muffler .
I can go hills now.

I found the butterfly plate was seized ,it robs heaps power of top of the crap exhaust manifold
Would you share a picture of your improvement? By the way some RD28 engines come factory with something like what you describe.

Oldbeaver
 

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Discussion Starter #10
Been a bit of time since I posted this

So I did [part] of what mightydato suggested, which was to drill a vent into the oil cap



I used a cheapo generic oil cap, not my oem Nissan one

I did get some power back from doing this

For power loss, clean little filter in lift pump supply bolt.
more info on this please
 

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Inside the banjo bolt that connects the fuel line to the fuel pump should be a little filter that no one ever cleans.
 
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