Suspected head gasket fail

[Chad]

Thought I’d start a new head gasket thread,, 69500 miles so about usual mileage. started to notice motor feeling a little lumpy light burbling I can best describe, also not quite as crispy,, so tonight plugs out, fuel pump fuse out, my cheap leak down tester was knackered,,so in with new compression tester ,number 1 cylinder 110psi, Number 2 110 psi,, 3-4-5-6 cylinders bang on 150psi,, Didn’t do the tee spoon full of oil thing and confuse results ,, so possibly would be higher readings, but I think I can be sure failing between 1and 2,, Ps all the plugs looked nice no oil,no build up carbon, or running lean, all looking good,, if I get time this weekend I might start to stripdown of motor and try to take some decent pictures to post for reference, .. “””Any thoughts views ideas welcome chaps,,

[Chad]

Ok for reference. Anybody doing a compression test. Just done compression test on 10k mile max engine, readings 165 ish psi, across all six cylinders warm engine , I did crank the motor over a couple more on this motor and possibly slightly warmer by a few degrees, but not sure it made much difference in readings!! “””Didn’t put any oil in cylinders,,, used a laser compression tester,, so I’d estimate my 65k motor has lost approx 10psi ish across the cylinders , apart from 1 and 2 ,, that show 110psi. Not sure what the lost 10psi -15 psi ish would equate to regarding HP. Comments welcome chaps. :whistl

[Chad]

Further addition. Let 10k motor cool, did a further check on compression just did about 4 -5 cranks on starter motor got 155psi ,, as compared to 69k motor readings 150 psi readings 4-5 cranks . So probably a lot closer that first thought ,, then took a new reading on 10k motor 1/2 tea spoon oil as some recommend , spun motor over 20 times on starter compression readings 175 psi 10 k motor.

[Chad]

Just pulled the head off ,As expected gasket gone between 1 and 2. Typical of the perfect design of the s54 engine gasket also gone on the centre section of the three layers 2 and 3 possibly torn as I pulled gasket off...hopefully block and head will be ok ,,hard to believe they didn’t do a better job in the reliability design,,,don’t you just love bmw

[Mike R]

It does seem strange that they squashed all the cylinders so close together, which means not much surface area of material on the gasket between the cylinders - way to go BMW

[Chad]

Just had chance to properly check the head and block, all looks ok so I can now breathe again, while it’s head is off ,I’m going to do rod shells,, pull one of the piston out and check end gap on top and central ring,if they within bmw spec they will be staying in, I’ll be disappointed if they are out of spec on a 69500 mile engine, but from what I worked out on 100k motor, I recon they should still be inside spec

[Chad]

Question to them that have done camshaft timing before?? Checked camshaft position before I pulled them out , image engine to be vertical,,, I noted at TDC alignment hole in inlet camshaft prity much vertical,,,but exhaust shaft was a few degrees past vertical approx 5-10 degrees, I’d have thought it should be vertical,, Ps I’ve ordered bmw alignment tool for tomorrow,, Question, is this few degrees past for exhaust correct ?? Or possibly a sticking exhaust vanos gear splined shaft..or holding advanced on hydraulic pressure ?? I was assuming alignment tool “holes”inlet and exhaust would be perfectly vertical so to speak..noted exhaust vanos gear was a bit troublesome coming out, ... answering my own question, yes they should be perfectly vertical so to speak,, checked with bmw checking tool .

[Chad]

Today dropped in a couple of ring sets in my csl 69500 block , for a comparison to 100 k Motor project,, oem ring set size 00 new top ring end gap measurements a fairly tight 0.20 ,,,,25 mm down cylinder, central ring 0.45 ,so almost perfect,, Then dropped in the npr set,, apparently same as oem 0 set End gap came out 0.30 top ring. Central ring 0.48 So also really good,, Possibly a safety bet at the top of the cylinder bore, will know more if I was to clean top 10mm of the cylinder,,, I’m going to take a piston out and measure the 70k rings see how they measure up as I’m doing shells anyway,, hopefully useful information regarding motor work,,,

[Chad]

Another fun day with csl 69500 mile motor,,rod Shells out ,, 5 out of the six rod side shells showing the copper colour,number six was the worst but still only measured up at just under 0.050,, tangs were ok but shell was a little loose so possibly spinning could have been getting close. ,, as usual cap shells not to bad number six the worst ,, Number 1 “least”worn shells looking ok “”. I’ve plastiguage Number one used shells for reference came,, came out as 0.045 to 0.050 ish.. so even though copper colour shows on some shells, they are still in spec,and not always fooked. ,,,, then I’ve pulled the pistons out of the cylinders,, just measured number one piston rings for now ,, turns out top 69500 ring measurements.. 0.35. Actually bmw spec outer limits end gap. ,, central ring unbelievably 1.30 mm So way past outer bmw spec. cylinder condition look really good crank journal look good ,, so my conclusion after these two separate csl motors strip downs’ anything past about 50-60 k miles rings are way past there best ,and shell getting close and probably need renewing to keep within bmw spec,, il do oil rings later,,,now done oil rings,end gap 0.75 mm, 0.25 outside spec.ok they are sacrificial. hopefully this won’t upset anybody

[Chad]

The big dilemma ,, do I aim for perfect piston ring end gap, use the oem 00 ring and go for min gap of 0.20 top ring and mabe have to ring file the tighter one’s ,,? , or go for std 0 size. And settle for 0.30 to 0.35 outside spec top ring . ??? “”. Update checked bmw oil ring in 00 size gives end gap of 0.10 so not really practical to tight,, end gap oil ring npr gaps up at 0.35 so bang on between spec,, so answered my question,, really have to use either oem 0 size or npr rings are good to go ,, In this 69k motor. Note top ring doesn’t wear that much, it’s the central ring and oil ring that really wears,,