G'day from Down Under...

[Kevin Elvey]

Max Capacity (FTE forum) has recommended I chance my luck here (probably got tired of me pestering him with my idiot questions)...

Only kidding, MC!!!

Anyways, I'm Kevin, an old (77) bushie living in Orange in the Central Highlands of New South Wales, Australia. I'm retired (sort of), and I live in a previously burnt out house which I have been renovating for the last thirteen years.

I bought my Effie (BigBeast) at auction 33 years ago from Elcom (the state electricity utility). They had a dirty big tank of creosote bolted on the back, which they had been using up in the Blue Mountains to rot proof wooden power poles ...apparently she was the only vehicle at the time capable of getting such a load up into what was pretty rugged terrain.

I currently use her just for trucking in building materials, and getting into the bush to areas where lesser vehicles can't go to get firewood for my wood heater; though I do intend someday to go around OZ in her!

Currently though she's not going anywhere, being sadly broken down for three months now, which is why I'm here, shamelessly trawling for advice on how to resuscitate her.

Three months ago, she had been running a little rough for the last few days and drinking more coolant than normal (head gasket?), but still going reasonably well. The day before, I'd gone out and got a load of firewood; but then next morning, without any other warning...she was dead.

The engine had cranked normally for a few seconds (with LPG, it takes about six seconds of cranking to get the fuel through the converter and into the engine); then it was like the load came off the starter motor, because the cranking note changed, as though it had suddenly sped up. I thought at first the starter motor had stripped its gearing; but then found that the engine was indeed still turning over. You could explain the increased cranking speed by a sudden loss of compression, perhaps; but I tested for that and got 125 psi on seven and 115 psi on the eighth. There was also for a while a sound which I couldn't localise, though it seemed to be somewhere at the rear of the engine--not a sharp sound like metal on metal, but sort of a chuffing noise (air coming in through the broken EGR vacuum tube or the loose inlet manifold gasket, or a head gasket?). It stopped eventually without me doing anything to the engine.

I checked the spark (orange and not super strong, but nothing new there--leads and dizzy cap are the originals, 38 years old). It's not easy with LPG to check that fuel is getting where it's needed, so I just shot some go juice into the air cleaner, but same result--not a single cylinder fired. Pulled the ignition plugs, which had been in there about ten years. They were surprisingly okay, though one looked a touch wet (oil), and another had some slight rust. So I started pulling more stuff off.

The innards of the fuel and air hoses, air filter and inlet manifolds were wet (and I do mean wet) with black oil, which I took to be residue from the LPG conversion process (liquid to gas). I drained the LPG converter (about a tablespoon full of oil), and was later advised by the techosavants on the Ford Truck Enthusiasts forum that it was more likely blow back due to either worn rings, a dodgy PCV valve or poor vacuum. The bolts fastening the upper inlet manifold were mostly little more than finger tight, possibly compromising said vacuum, and the lower inlet manifold had white gunk in the port serving the cylinder with the slightly rusty plug, possibly explaining both the rust on the plug and the loss of coolant.

The tube connecting the EGR valve to the lower inlet manifold was broken clean off, and the tube running from the Thermactor air pump (removed actually, with the line capped upstream of the air bypass valve, though this cap had actually fallen off) also had a big hole rusted in it.

What was most disturbing was that the majority of my pushrods were bent, two of them badly. I cranked the engine again, and all appeared to be lifting and falling, meaning hopefully that the hydraulic lifters were functioning as they should? The compression test had also indicated that I had sticking valves (non sequential or irregular step increases to maximum pressure); so I can understand the thinking that would have me remove the heads for further inspection. I'm feeling really uncomfortable about that, however, due to what I've realised through the FTE forum is the superficiality of my understanding of matters mechanical. I have taken a head off once before (series 2A Landrover); but I can see now that I was blissfully ignorant of so much...it was a wonder that the engine ever worked again.

Here is where I am at the moment...

My Effie died of a combination of ills: (1) poor spark ; (2) an air filter clogged by blow back; (3) low vacuum; (4)bent pushrods (6 at least, a couple badly) shortening valve operation. These factors weren't enough to stop her when hot; but were enough to prevent starting when cold. Does that sound plausible?

The bent valves could perhaps be explained by over revving the engine (possibly up to 5000 rpm) especially when I was younger and a bit of a hoon (140 kph along dirt tracks); but that would mean I've had bent pushrods for decades. Is that likely?

My thinking is as follows: just replace the pushrods, gaskets, ignition leads, dizzy cap, air filter, ditch the emissions crap and block off the holes, get her going...then convert her back to petrol and run a few bottles of valve cleaner through her to fix the sticky valves issue.

Puhlease tell me I don't have to take the heads off!  

[Gary Lewis]

Welcome, Kevin!  Glad you joined.  

What part of "down under"?  I ask because we have a map (Bullnose Forum/Member's Map in the menu) and we could add you if you'd like.

As for troubleshooting, you won't get as much visibility here as you would in the main section.  But I'll tell you what I'd do - run a leak-down test.  That will tell you a lot more about valves, head gaskets, cracked heads and block, etc than anything else.  Then you can decide what to do from there.

Having said that, the fact that it ran one day and doesn't the next doesn't suggest bent push rods, leaking head gaskets, or the like.  It is more binary than those things usually manifest.  So I'm thinking ignition or lack of fuel.  And since you shot "go juice" in it with no effect it probably isn't fuel.

But, you also said it spins freely like there is no compression.  So it doesn't add up.  Perhaps someone else has a better idea?  

[Kevin Elvey]

Thanks, Gary, much obliged for the welcome. You're a friendly lot...

Happy to go on that register: I'm at Orange in the Central Tablelands, a hundred odd clicks west of the Blue Mountains. I'd heard about the leakdown test on the FTE forum, but doesn't it require specialised equipment?

I have had mostly electrical problems with her, so you could be right there.

All I know is that when initially cranking the sound suddenly changed. It was three months ago now, so my memory may be faulty, but I think that the engine spinning faster was my perception.

Anyway, good to be on board.

Kevin

[grumpin]

Welcome!

[Gary Lewis]

Kevin - I put you on the map, but may have gotten the wrong Orange, although I didn't find others.  So please advise.

As for the leak down test, it requires a source of compressed air, although not all that much, and the tester kit itself.  Here's a link to some on Amazon and you can see they start at $17 US.  However, I wouldn't buy one that doesn't have two gauges as it is the difference between the two that tells the tale.

The way it works is that you bring the input up to some fixed pressure, which is usually 100 psi to make the maths easy.  Then hook the other side into the spark plug hole of a cylinder that is on TDC on the compression stroke.  If all is well there will be little leakage, which will be registered as pressure loss on the 2nd valve as there's a very small orifice between the two valves.  So if #1 is at 100 and #2 shows 90 you have a 10% loss.

Then you go around listening to find where the loss is coming from.  In the carb means an intake valve is leaking.  In the exhaust means its valve is leaking.  Bubbles in the cooling system mean you have a head gasket leak or a cracked head or block.  And sound in the sump means the rings are leaking.

I've seen compression testing saying there's no problem, but a leak down test proved why the engine idled so roughly - adjacent cylinders in the firing order had bad valves.

[Kevin Elvey]

Thanks, mate.

[Kevin Elvey]

Regarding location, Gary...yup, you nailed it. If you're ever in this part of OZ, knock me up and I'll introduce you to some of the best cherries you've ever tasted. Just don't expect any oranges, though...they're about the one thing we don't grow!

I can see that the leak-down test, as described by you, really is the go to test. I'll have a scout around here to see what's available.

[Kevin Elvey]

Bit of an update: my decision here was not to go into the engine any deeper (as in removing the heads)...just replace all the push rods and get BigBeast back on the road. Thing is, in doing a precautionary check of the torque of the head bolts, I found one which was loose. Figuring that it was snapped, I tried to drill it out, and was going great guns until coolant came gushing out! Two possibilities: either I'd gone right through both the snapped off piece of the bolt and the block, or else the bolt was intact and it was the thread of the block that was stripped (possibly on initial assembly), and I'd been drilling into the block from the start. Anybody care to tell me how long the bolt should be so I can figure out if it has actually snapped?

Either way I've got a hole to plug, and likely a thread in the block to repair.

Naturally it's the bolt furthest from the front, so it's back almost under the firewall and hard to get at. I'm thinking it would be easier if I did take the heads off after all.

What might be other reasons to take off the heads? Would decarbonising and lapping the valves be something you would want to do at 103,000 miles? I guess replacing the valve seals would be a no brainer, considering that the rubber in them has to be nearly forty years old, and hence kinda brittle, I guess. Also, with the cause of my six badly bent pushrods unresolved, it would be good to get a look inside the cylinders anyway.

Anybody care to comment?

[Gary Lewis]

The 302 apparently used two different lengths of head bolts, as shown below.

I think you can thread what you have, use thread sealer on the bolt, and recover.  But while you have the heads off I'd lap the valves and replace the guides and seals.

[Kevin Elvey]

Thanks for replying, Gary.

After converting your data sheet to millimeters, my bolt comes in at about 3 mm shorter (approximately 55mm) than the shortest bolt listed there (2 19/64" converts to 58.34mm). I guess I'll know for sure what's what if I do decide to pull the heads, as I can of course then compare that bolt with the rest. The 14 in front of each measurement in that data sheet: does that denote the thread count?

I feel reasonably okay about replacing the valve seals: that doesn't appear to be too technically involved a process. I'm not so confident re the valve guides, however...wouldn't that be a job for the engineering shop?

I'm still looking for a conclusive answer as to why I have so many bent push rods. Malfunctioning hydraulic tappets are one possibility, I believe. How do you check a tappet...what do you look for?

Thanks again, mate.

[Gary Lewis]

If the bolt is that short then it may have been replaced.  But you've had the truck for 33 years and until recently it has been reliable?  That doesn't add up.

As for what bent the push rods, someone on here recently had bent pushrods due to bad fuel.  It gummed up the valve/guide clearance and the valves didn't want to open.

But didn't you say you are running LPG?  If so I wouldn't think you'd have the same problem.  So about all I can imagine then is over revving.  But a 302 shouldn't have problems with 5000 RPM, so maybe bad oil?

The page at Documentation/Engines/General Engine Service has the 1985 factory shop manual section entitled General Gasoline Engine Service, and it has a discussion about lifters starting on Page 4.  If your oil had something gummy in it the lifters could fail to compress and that could bend pushrods.  So check out that section on how to clean lifters.

And yes, valve guide replacement does require some special tools so I'd take the heads to an engineering shop.

[Kevin Elvey]

Thanks for that, Gary. I went to your suggested resource and checked out the advice on lifters...there's a lot there to digest. I'll get back to you when I think I understand it all.

Today I'll maybe bite the bullet and take off the heads...and yup, they'll be going straight to an engineering shop!

[Gary Lewis]

Good luck!