Time for surgery ?

I need to get this off my chest, not a happy bunny! Have been having a bit of an issue with my trusty '91 RRC. It has been misbehaving with an occasional rough idle and stalling and it has been getting worse over a couple of weeks, it is now laid up as too poorly to drive.

I looked through the ignition system, it's been a while since it had any attention so standard stuff, new rotor arm, cap, plugs and leads (genuine parts, no pattern rubbish please!). Swapped the ignition amplifier fired it up, seemed good, set ignition timing ran like a top but not for long, the poor idle and stalling came back, real problems coming off idle. Press the pedal and it would misfire like mad and stall. Put a new coil on it to take that out of the equation but no difference. Checked voltage, battery O.K. alternator output satisfactory.

Thought I should check the efi side of things, checked throttle pot, did a substitution on the ecu still no better. Looked at fuelling and found a leak on the fuel return, so while I was about it I decided to put on a new pump and filter, checked the pressure regulator was working and still it misbehaves. Did a substitution swap on the air flow meter, no difference so it's not that.

I took the plenum and ram housing off, all good, put it back - no difference. I did a compression test a couple of weeks back, good results but one pot down so maybe head gasket but symptoms feel like fuel starvation so maybe an inlet air leak? The valley gasket does have a suspicious damp patch at the front so maybe.

The other possibility is the camshaft, it has never been changed and although the engine has AFAIK only done 103k perhaps it is time. I suppose the question is whether a worn cam could explain the issues I am getting, the rough idle and stalling is worse when the engine is warm. The odd thing is if you can get the revs up it will happily rev freely with no apparent issue, dial in a bucket load of ignition advance and it will idle a bit better but that is not the answer. My thoughts are if the cam is goosed the valves won't open properly and with warm oil, the followers may not have full pressure at idle but when cold, the oil is thicker and pressure better so it runs marginally better, this might also explain why it seems to rev fine at higher revs as the oil pressure will be stronger.

So, on the basis there is a lower compression reading on one pot, the valley gasket might be leaking and I have doubts about the cam I think a top end overhaul may be in order.

Any thoughts welcome. Cheers.

Bet there's been some fruity language
Not much left kev.
Is the low comp near the water jacket?
Is the distributor fecked / not advancing?
Is the fuel dodgy?

Hahaha, yes I did try the harsh language approach but that didn't work either!

The low pot was no.6, can't find where I wrote down the results but all the others looked O.K.
The distributor is fine, made sure I checked that out and the fuel is fine too.

So...... have decided I'll bite the bullet and go for it, will deliberate over a camshaft and probably go for new lifters, push rods and timing chain while I am at it, would be silly not to. Seems the perceived wisdom is to go with a Kent H180 cam, a bit more expensive than a standard 3.9 cam but should pep it up a little. I'm not really interested in looking for big power/torque gains so won't be going mad. Once I get off my behind and do it I'll post what I find and how the cam job goes.

Cheers.

Did you check tp increasing straight off idle as well as idle voltage?

cooltide said:

Did you check tp increasing straight off idle as well as idle voltage?

Click to expand...

I certainly did, base voltage is good, scaling is good. I did hope it was just the throttle pot but a vain hope. Never mind.

Seeing as it has stopped raining/snowing/blowing a gale I ventured out to assess where I am at. While I have been checking various things the misfire has steadily become worse so won't be spinning it up again until I have had at it. Anyway, I noticed evidence of a bit of oil at the back near pots 5 and 7, had a closer look and head gasket failure appears to be the culprit. Might also be a small weep on pot 2 as well so not surprised it has been protesting. Took the oil filler cap off and saw the tell-tale mayo so it appears the primary issue is a well stuffed head gasket (or two!).

A head gasket job isn't too bad but I have convinced myself I should do the cam while I am at it so I'll be going for it in a couple of weeks time when hopefully the weather will have improved and warmed up a bit, I hate working on stuff when it is freezing cold and you can't feel your fingers.

I'll let you know how it goes!

Just a quick update, I've started stripping the engine down, plenum, ram housing and inlet manifold removed, rockers, lifters and pushrods out. The inside is actually pretty clean (this is good!). No discernible play in the rockers/rocker shaft, cam looks quite good too but some slight wear, I'll know more once I've taken it out. The cam followers are mint with no visible wear but I did replace them about 30k ago, the original ones were dished but the current ones are very good.

I've found the small breather at the back of the near side rocker cover was blocked but it's probably been like that for some time (like 6 years+).
So, hopefully this weekend I'll have the timing case and heads off then a day cleaning parts followed by re-assembly with new cam, lifters and pushrods. Should be fun, hopefully I'll have no issues as long as I can move the air conditioning condenser without incident all should be good.

The tear down continues. Timing cover off, my home made crank pulley locker worked a treat. Pulled all the cam followers, found one that was a bit naughty, looked at cam lobe and found some damage so just as well I decided to replace the cam. Speaking of which, trying to get the cam sprocket off was a bit of a battle, it was really stiff, think the key might have moved although not sure how. My next challenge is to get the key out (might end up needing a new one!). The only let down so far was one of the water pump housing bolts sheared off so that will be one more job to do, I hate drilling bolts out, unfortunately it is one of the bolts that I cant drill through and replace with a suitable nut and bolt through the casing and if one has snapped you can be sure others will do the same, oh the joys!

Anyway, see what happens this weekend, fingers crossed.

Try some left handed drills to get the broken stud out theory is if the drill grabs when drilling it often unscrews the remmnant of sheared stud.

Took the other head off this morning and No.2 looks a bit clean as in steam cleaned so that's a fairly conclusive case for a blown head gasket although I can't remember which pot was down on compression, pretty sure it wasn't 2 but the evidence clearly says otherwise. Hey ho at least I haven't wasted my time.

I'll be in to cleaning parts next before re-assembly with the new Kent H180 cam, quite excited to see how much of an improvement I get from the new cam as well as sorting out the head gasket issue and worn original cam. Luckily I don't have to rush but all things being equal I hope to be up and running again by next weekend, still have some tin worm to sort on the inner wing so might do that tomorrow.

Cheers.

Not a bad day today, stripped both heads down, cleaned the valves and lapped them. All pretty good, not much carbon in there and it was soft and easily removed. Valves and seats looked reasonable no evidence of excessive play in the valves/guides so all is dandy. Didn't fancy welding today so didn't fix the inner wing yet but plenty of time.

Put the new cam in the block so as soon as the new water pump and cam gear arrive (tomorrow?) I can get on with putting it all back together. If it wasn't for waiting for parts I could probably of had it done today but it's nice not to have to rush. Decided to helicoil the hole for the snapped bolt on the waterpump so drilled out what was left and filled with chemical metal where the drill wandered slightly, should be alright have used chemical metal for filling and helicoil before, works well.

More spannerin' tomorrow!

Another good day yesterday. The cleaned heads went back on and all torqued down but don't you just hate that horrible feeling of impending doom as the torque wrench turns and you're waiting for the click or the sinking feeling as a bolt strips a thread! Anyway, got away with it again, happy bunny.

1/4" UNC helicoil kit turned up in the post, water pump bolt thread repaired and all good.

New water pump and cam sprocket arrived late in the day but pushed on so cam sprocket and new timing chain fitted on to the new camshaft, TDC marks align nicely so looking good. Water pump mounted on to timing case so getting really close now. Todays goals are to drop the sump off, clean it up and fit new gasket, then check cam follower pre-load. Assuming all that is good then I'll crack on and prime the followers then re-fit sump, timing case and rocker covers then with luck get the inlet manifold, ram housing and plenum back on. and re-attach them. That should then only leave the air con condenser to re-fit, install radiator then do the plumbing, fit oil filter, add oil and water then the big moment of sparking it up.

The sun is shining in North Wales this morning! Hopefully a sign for another good day.

Yesterday I spent ages cleaning bolts and replacing ones that looked past their best. Took the oil pump off and it looked pretty good, while I don't normally bother I did pack it with petroleum jelly.

I checked the lifter pre-load, what a pain that is. I have to admit struggling a bit; no shims the preload looked massive, so went with the thickest shims resulting in not enough. The thinnest shims would have made little difference so went with the intermediate shims and as far as I could tell this gave me a preload in the accepted range. Then I removed all the followers to prime them with oil and put them back in.

I turned the engine by hand to check everything was doing what it should, nice and smooth no nasty notchiness or odd resistance and certainly no valve to piston contact so I am pretty happy.

On to the sump, dropped it off and gave it a good clean then had to decide whether or not I would use the gasket or go with sealant again. I decided this time I would go the gasket route, seeing as I had a gasket I thought why not. After cleaning all the sump bolts ( they were a bit grim) I degreased the sump and the bottom of the block, applied gasket sealer and the gasket then put the sump on - all looking good.

Next I decided to fit the timing case. Again gasket sealer applied first but I noticed the gasket wasn't sitting right at the bottom. Odd I thought! then it dawned on me that these engines don't normally have a cork gasket so I carefully trimmed a couple of mm off the gasket and perfect fit. So offered up the timing case, again I didn't account for the gasket so had to crawl back under the engine to loosen the sump bolts to drop the front of the sump down a bit to get the clearance (what a numpty!). After faffing about had a nice fit so bolted it all up and torqued all the sump bolts, hopefully nothing will leak - time will tell.

Timing case on so the next step was to put the bottom pulley on - slipped nicely in to place and the TDC mark lined up perfectly. Fitted my crack locker and got stuck in to the crank bolt, that thing is super tight 270Nm or 200 lbft of torque, so torque wrench maxed out and then some but a length of scaf pole makes it easier. so popped off the timing cover bolts again and coated them with thread sealer then torqued them up and all is well.

Todays targets are to get some oil in the sump, fit inlet manifold, ram housing and plenum, maybe get the condenser back in place and fit the radiator. While I'm here I'm going to moan - when you buy a gasket set for a 3.9 why oh why do they still include the injector rubbers from a 3.5 flapper that are no good at all! Anyway, I went on-line and found a company that sells the right injector seals at sensible money and got them all fitted up. If you decide to change your injector seals make sure you get the right size.

Going to get back at it, in the home straight now, hope to fire it up very soon.

Got it all back together yesterday and fired it up! The good news is there were no leaks and it runs. the bad news is that the misfire and rough running that started it all off is still there, to say I was a bit miffed is a bit of an understatement. The running issues made trying to break in the new camshaft a bit tricky but I think everything is O.K..

I chucked some redex in the tank and after a while I managed to get something approaching a stable idle. The problem really feels like fuel starvation but I can't for the life of me nail it down. The fuel pump is brand new and there are no fuel leaks. Unfortunatey I don't know of a way to test the injectors on the car so I can't do much to try and narrow it down. Anyway I will persevere, I will get this licked!

I'm going to double check the ignition side of things but new rotor arm, dizzy cap, leads and ignition amplifier have been put on. The coil is new and is firing out a stream of big fat sparks so that kind of says ignition amplifier and coil are fine. I might disassemble, clean and re-fix the main earth points including the EFI loom.

If I manage to get it sorted I'll post an update, going to go and sulk in a corner with my workshop manual now.

O.K, finished sulking now!

Have spent the last couple of days going over everything. Checked ignition and efi no faults found. Ran a compression check, no issues here either then hooked up a vacuum gauge - HMMMMM. Vacuum was low and moving around a bit, could this be valve timing? an inlet leak somewhere? iffy timing? duff plugs? sticky injector? the possibilities were numerous.

My biggest concern was valve timing. I decided there was nothing for it but to take the top off again, so off came the air flow meter, plenum, ram housing, injector rail, inlet manifold and valley gasket. First looked at the cam to see if there was any sign of damage after the rather erratic break in but it looks O.K. Saw nothing else obvious but an air leak might not be immediately visible, so anyway, I decided to look at valve timing. I bought a timing disc which frankly didn't work with the engine in the car so messed about a bit and came up with an alternative. Took off the bottom pulley (again!) then carefully marked up a piece of masking tape using the pulley timing marks then measured the distance across all 24 degrees then marked up a longer piece of masking tape and attached it to the pulley. I needed to see 108 degrees after TDC to check for max inlet valve lift on No 1. Using a small triangular needle file I scribed a mark on the pulley then slid it back in place.

I mounted a dial gauge so I could see when No 1 inlet valve was at max lift and then turned the engine over on the bottom pulley and my improvised timing mark was spot on! I was happy it worked but having now eliminated late valve timing as a possible issue I was no further forward. Set the engine to approx 3 degrees BTDC as my base for ignition timing.

Anyway, I decided to put it all back together, took the risk of re-using the valley gasket (no choice, haven't got another one!), I took extra care to ensure everything was sealed then built up the top end again.

So, the moment of truth, had it worked?













YESSSSSSSSS!

The Rangie lives! (well, for now anyway). Now I can turn my attention to the rust repair I was threatening to do at least a week ago.
Cheers.

So what was it? Valley gasket air leak?

I was wondering that to

johndregg said:

So what was it? Valley gasket air leak?

Click to expand...

Can't say for sure but would say probably. Before I took it all off for the second time I did try spraying all over the top of the engine with water to see if that made any difference but it didn't so I suspect valley gasket as some places the water wouldn't have reached. I re-used the gasket but this time applied gasket sealer even though normally the gasket is applied dry.

All I can say is I am so pleased it is running again. Stuck it on my gas analyser and all looks good, certainly it should walk an emissions test.

Anyway, thanks for the interest. Cheers.

Well done kev pleased you got a result in the end and its all working

So to close this one down, I gave it a road test today and all seems good, pulls well.
Have had to make some changes though to account for the new camshaft. Ignition timing has been advanced to 10 degrees, CO Trim on the MAF has been raised to 1.35v to give as near as possible 1% CO at idle. HC has come up bit at about 500ppm but the settings are well within the limits for MOT emissions on a non-cat engine. I also found the base idle setting was way too low so have raised that up to where it should be at 500rpm. Hopefully that should be it for a while on the engine.

Good luck to all of you with your projects. Cheers!