K-jet non starter after cylinder head overhaul

Firing order = Correct. Easy start = failed test. Compression test = 3 cylinders 0, only no'3 had good compression

Not sure what the issue could be. The head was skimmed, used a metal gasket this time, new head bolts in the correct sequence (not oiled tho!) Cleaned the bottom end surface, but not with anything aggressive. Maybe the cause?

Any suggestions before I rip it all apart again..... not a happy camper!

The rings were fine, checked by pouring in petrol & it did not leak through. The cylinder walls seemed in good condition too. Did run about 100miles with blown head gasket before noticing though, hence the petrol test to see if the rings were shot.

 

0 on 3 cylinders mmm are you sure that the cam/piston timing was good there is a chance pistons have touched valves if there's no compression at all the heads prob going to have to come off any way mate, not what you wanted to hear I bet.

 

Sounds like a valve clearance issue, somehow. Can you spin the buckets when the lobes point upward? To lose all compression something must be badly wrong. Can you get someone to crank it over with the rocker box off (arrange a pushbutton or switch live feed to the solenoid if one manned) and give it a good looking at. We had a misfire on my mates cossy at a rally fairly recently, diagnosed as we got home as the exhaust cam had snapped on no4 !
You didnt stuff cloth down the ports tom keep the muck out, did you?

 

Used the same valves & buckets, but the workshop may have got the valves mixed up.(Will it make a difference?) I definitely mixed up the buckets, but the cylinder head workshop said its irrelevant. Will check if the buckets spin, have a 3rd hand fortunately.

No cloth used!

Thanx for swift response!!!

 

Ideally the valves should be put back where they came from however if they were lapped in it shouldn't have mattered. Did they pressure test the head when it was overhauled? I'd have said the buckets would't be the issue if compression has gone the valves aren't closing when they should.

 

Yes I can spin any of the buckets when the lobes point upwards.

 

When I overhauled the engine a few years ago I did notice the valves not closing 100% due to the fact some of the valve seats had been re-done & sit lower in the head & the new valves had to be ground down to compensate. If they mixed up the valves it could definitely be the problem. However it looked fine when I bolted in the cam before attaching to the block, but I didnt rotate the cam to check if the valves were indeed all closing 100% which I'm starting to regret not doing right now!

 

Is it a hydraulic or solid tappet engine?

Does the oil pressure light on the dash go out when you're cranking it over. You might need to pump up the lifters with oil pressure to get compression. It's a bit extreme if you've got no compression though.

 

Its a hydraulic head, & the oil light does go out on the dash. Have cranked the engine so many times & appears to be a bit of oil circulating in the head judging by the splash cover.

 

Can't see the lifters being primed as the issue. If you get an old plug and cut the top and centre out of it, weld some 10mm pipe to it you can connect it to a compressor to fill the cylinder with air. (valves shut) leakage should be obvious then. It is possible to get head studs bottoming out before clamping, something I always check with a heavily modified engine. Shorten as required.

 

I would say its going to be valve related. Either the valves have dropped, the valves are cracked or the springs have gone. Sounds like somebody didnt do a good job on you're head at all. The only other thing it could be is a snapped cam but not likely, I'd get back in touch with the workshop that did it and tell them exactly what you have done and give them the compression test figures. Then demand that they get it sorted. They were wrong in saying that the hydraulic follower order is irrelivent because it is, the follower will be worn to the cam lobe thats been pushing it. If you change the order you will wear out the cam lobe or follower much quicker.

 

They do say to put valves back in where they came out. I still say head off 0 compression means something a miss mate unless anybody has any other ideas usually no compression points towards valve valve timing/ring issues but she ran fine before so its something head wise

 

Going to pull the head off again tonight & will keep u posted!

 

Before you do that, turn it over on the starter with the rocker cover off. It'll splash a bit of oil around, so some well placed rags would help to reduce the cleanup afterwards. You should be able to see if the cam is turning correctly (ruling out a broken cam or a sheared/missing keyway on the cam pulley), and if any of the tappets are sitting differently from the others. A broken or dropped valve should show up in the height that the tappet is sitting at, if you take the cam off, so there are some diagnosis steps you can do before taking the drastic step of pulling the head back off.

Also, if the head has had a heavy skim, have a look at the back of the head to check that it's sitting down properly on the gasket, and not sitting proud on the dowels. I've not seen that on an 8v, but worth a quick look.

Did you clean out the head bolt holes of any residual oil? That can cause the bolts to bottom out (as per Jon's suggestion) and could possibly lead to a cracked block. Hope not, obviously!

 

Head been off already, cam rotated & valves all look to be fine. The skim was not excessive, but will have a look to see if its sitting proud on the dowels. The threads were cleaned out on my first head install to remove excessive oil.

The cylinder head workshop reckoned the hydraulic followers need to be pumped up as mentioned by Mike H, but I have been cranking it for a good ten minutes & no changes to the result (with & without spark plugs)

Timing all fine, so bit stumped to be honest... - thanx for the replies!

Currently the fan belt is not connected for w/pump & alternator, but doubt that has any bearing on it not firing up.

One other strange thing happened while working in the engine bay before installing the head. Some how a tool managed to short on something close to the coil. Not sure exactly what, but definitely was not the battery terminals. (Should disconnect battery I know!) I wonder if I damaged something?

 

if the head is off take cam out turn over and put fuel in each combustion area the valves will be shut with cam out so you will see if there is leakage.
You should have alternator belt on as it helps ignition amplifier, seems weird that it all looks fine yet still gave 0 compression that points to a leak allowing air to leave bores and not compress.

 

my leakdown idea is still relevant. make a leakdown tester and find out where the air is going. get a second pair of eyes to help you, as sometimes making one false assumption without realising it can throw you. its happened to me

 

Unfortunately I do not have a compressor or welder to make the leakdown tester, unless there is another way to knock one up? (which I have attempted)

Have primed the oil pump & dash light was actually coming on but made no difference. Taken the cam cover off & can see there is oil all around the followers while the engine is being cranked so I dont think that is the issue. Oil was not squirting everywhere though, just accumulating around the followers.

The gasket looks well seated at the back & was correctly installed on the dowels & I made an effort to clean the surface of the bottom end before placing the head back on.

I tested the compression once again & still only #3 had decent compression.

The head bolts felt pretty good when tightening them up, usual degree of effort towards the last few turns. Wondering if 1.8L block head bolts are different in length to 2L head bolts?

Firing sequence correct/ timing marks aligned.

However I can see some slight moisture on the head gasket between the head & bottom end, but only a tiny amount. Probably would burn off if she ever did fire up!

 

Remove the inlet manifold and shine a torch down whilst someone turns it over. Can you see the valves moving ?

 

footpump would do instead of a compressor. would be useful to write the compressions up here. can anybody off the forum visit you? I am in derby/birmingham mid week, en route from the NE