knock when hot

tottot · Oct 3, 2013

My series 3 diesel has started to knock but only when hot[normal running temp] on start up it's as before only usual diesel rattle but as it warms knock gets louder with more on acceleration and a slight miss.Other symptoms are blue smoke and oil in the manifold.Thoughts all

.Have started strip down and will let you know what I find.

divie · Oct 3, 2013

When you get the head off take a real good look at the hotspots. Mine started with similar symptoms of some smoke, occasional miss, bit of a knock then it all went tits up.
A hotspot broke up wrecking the head. Top of the block and a piston got damaged plus general carnage. I bought another engine which turned out to be in the same state.
I had to machine 0.015" off the top of the block and the same off a new set of pistons then rebuild.
It may have been better to go the TDI route but I had not got time for all the extra work.
Make sure the hot spots are not loose in the head and good luck.

tottot · Oct 4, 2013

divie said:
When you get the head off take a real good look at the hotspots. Mine started with similar symptoms of some smoke, occasional miss, bit of a knock then it all went tits up.
A hotspot broke up wrecking the head. Top of the block and a piston got damaged plus general carnage. I bought another engine which turned out to be in the same state.
I had to machine 0.015" off the top of the block and the same off a new set of pistons then rebuild.
It may have been better to go the TDI route but I had not got time for all the extra work.
Make sure the hot spots are not loose in the head and good luck.

Head now off and the hot spots are still firmly in place[that's the good news]However there is a chunk missing from the edge of number one piston about an inch long and the ring seems to have broken up and made it's way into the combustion where it's remains are embedded in the top of the piston. There is a little damage to the head its self but the exhaust valve needs replacement ,the bore has only some light scoring and very little wear.Am hoping that a replacement piston and valve will sort it but cant remember if piston change can be done with out removing crank. This landy is just a farm runaround[it does the job of a quad but I stay dry] so will do only the min to get going,if engine out the may just find something else to go in.Cheers

divie · Oct 4, 2013

Yes you can change piston with engine and crank in situ. Try and hone/glaze break the bore before fitting the new piston. Valves and guides are cheap enough but I had to ream my ****part exhaust valve guides once fitted.
I know it is a ball ache but do remove the injectors and re torque the head after warm up to prevent premature head gasket blowing. Do it again after 400/500 miles or in your runaround case after winter when weather picks up. Enjoy the tinkering.

tottot · Oct 4, 2013

Thanks for the info divie,the last time I opened up a two and a quarter diesel I was a mere youth.The old landy not only keeps me dry but is cheaper to run than a quad and it's unlikely to get nicked.Cheers again.

tottot · Oct 7, 2013

Have now removed damaged piston an cleaned others to find markings but don't understand them. On the survivors are the letters BHB in a circle and ZAB/ H, also the number 514117 and in very small print D76,The D may be an O hard to tell. Any info welcome thanks.

divie · Oct 7, 2013

Not sure of those numbers without looking at parts CD.
Can you measure the bore ? From memory a standard bore is 3 9/16" (3.562") any oversize on that will be + 0.020/+0.030/+0.040" etc.

Blackburn · Oct 7, 2013

what does 76mm convert to ?
76 mm = 2.9921 inch

divie · Oct 7, 2013

Yes that conversion of 76mm is correct, however I seem to remember when I brought my micrometers home from work during my rebuild it was 2"to3" for mains and 3"to4" for bores. Memory as I get older does fail me though!

jamesmartin · Oct 7, 2013

sound like original pistons , std pistons are letter stamped for factory build, to match pistons to blocks to cater for machine tolerances, pistons later suplied for rebuild arent graded like that and just come as std or plus 10 ,20 etc but usually only plus 20s and 40s are now available, new pistons can vary up to 5-6 thou so bores are machined to actual piston size minus 2 thou for honing and piston clearance,std bores are 3.562 inch,(90.47mm) and to measure for exact wear you measure just below top ridge at top most part rings sweep, across the block , then measure fore and aft , measurement at bottom of bore should give you bores original size, it does need doint with a proper bore comparitor or guage

tottot · Oct 7, 2013

Looks like I need to borrow a good micrometer.Thanks everyone. ps the motor is a strange light green,could this mean a rebuild by someone?I seem to remember BL did this at one time.

divie · Oct 8, 2013

Millitery rebuilds are a sort of duck egg blue. My three bearing engine was a sort of light green but is not an original fitting. Engine number on mine is for early petrol so at some stage a petrol block has been used for a diesel engine. I have it running ok but always wonder if the camshaft set up is correct, I know the blocks are common.

tottot · Oct 11, 2013

divie said:
Millitery rebuilds are a sort of duck egg blue. My three bearing engine was a sort of light green but is not an original fitting. Engine number on mine is for early petrol so at some stage a petrol block has been used for a diesel engine. I have it running ok but always wonder if the camshaft set up is correct, I know the blocks are common.

The petrol/diesel camshafts do differ both in lobe hight and timing so although a diesel may run on a petrol cam I doubt it would go well. Have found that the graded piston lettering[ZAB/L BCD/L ect] represent a difference of just .0005 in,and was/is only done as James says on standard pistons to get an extra good fit.Have not been able to beg steal or borrow a bore measure but there is little wear[no bother getting the piston out] and it measures standard across the top with caliper as standard, so will order a standard piston and see if this will do?

Blackburn · Oct 11, 2013

I believe you can check the bores by inserting a piston ring and measuring the gap in the ring!

divie · Oct 11, 2013

Blackburn said:
I believe you can check the bores by inserting a piston ring and measuring the gap in the ring!

Do not try that with ****part rings. I ended up using + 0.040" rings (not from blue box) in + 0.030" bores and filing the ends to get the required gap. The +30 pistons from blue box where used but the ring gaps when checked where around 30/40 thou, Do the maths they would almost go in a + 20 bore!

tottot · Oct 19, 2013

Update. Piston now replaced and also big end shells for all four,the white metal was a bit thin.[used to rev the nuts off it on 4x4 trials]Have now started on the head,and have never seen such gummed up exhaust valves, hardly any space for the gas to escape, was chipping it out in chunks. I guess three years of just trundling around the farm hasn't helped, nor the exhaust pipe under the crossmember being flattened to a third of its size.

divie · Oct 19, 2013

I have added a 2009 RAV 4 to the stable which does not seem to go well for a 177 hp /400 nm torque (295 ft/lb) engine.
My theory is previous owner did short journeys, I have filled the tank with Shell V Power diesel and think it is showing some improvement. Maybe the odd additive or tank of posh fuel may help you.

tottot · Oct 20, 2013

divie said:
I have added a 2009 RAV 4 to the stable which does not seem to go well for a 177 hp /400 nm torque (295 ft/lb) engine.
My theory is previous owner did short journeys, I have filled the tank with Shell V Power diesel and think it is showing some improvement. Maybe the odd additive or tank of posh fuel may help you.

As mine is off road only it runs on red diesel. I was thinking more along the lines of fix the exhaust and give it a good thrashing now and then. The 200 I put in my 90 was a low mileage and short journeys motor and at first was getting through a liter of oil every 500 mls or so,but now after a couple of years of being worked properly it goes better and oil consumption has dropped right down.Cheers.

tottot · Oct 30, 2013

ornament

tottot · Nov 9, 2013

Motor now back together running and going well enough,some blue smoke but a whole lot less than before.Thanks again to all who helped.

knock when hot

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Attachments

Well-Known Member

Similar threads