Topic: 74 CJ-5 engine trouble.... please help (Read 11933 times)

henrycj5 · « **on:** August 07, 2006, 10:07:41 PM »

I have a 74 Cj5 with a straight six. I have just had the engine completely rebuilt (for the second time - long story so I won't go into it) replacing EVERYTHING.

Started the engine up and it sounds like a sewing machine with no power at all. the lifters and rocker arms have been replaced twice and the camshaft is new but the rattle is definetely coming from the top end. Makes no difference once the engine is hot or cold, (although I swear it's ever so slightly better when the engine first starts although I could be wrong)

Any ideas - please feel free to pass them on. And apologies for the moaning! :roll:

Anonymous · « **Reply #1 on:** August 07, 2006, 10:27:04 PM »

Hi Henry, this sound like a problem for bubba. But you may have to wait awhile he has not been on for awhile.

trent · « **Reply #2 on:** August 07, 2006, 10:32:36 PM »

Do you have good oil pressure?

henrycj5 · « **Reply #3 on:** August 07, 2006, 10:40:06 PM »

yep 60 psi

trent · « **Reply #4 on:** August 07, 2006, 10:48:46 PM »

And there's oil making it's way to the rockers/lifters?
It also may be worth inspecting the exhaust manifold for cracks!

henrycj5 · « **Reply #5 on:** August 07, 2006, 11:00:45 PM »

yeah think so. I'm no mechanic but the guy who rebuilt the engine informed me that there is oil getting to the top of the engine.
exhaust manifold is new and I've also fitted performance exhaust headers.

someone mentioned replacing the pcv valve? never heard of a pcv valve, have you?
Others have mentioned changing the grade of oil in the engine. I'm currently running on 15/40, should I change?

Anonymous · « **Reply #6 on:** August 07, 2006, 11:04:05 PM »

If I am right the pcv valve is on the rocker cover, on my cj it is near the bulk head and it should have a pipe running to the air filter. See if it is blocked and if so change it, they are cheap to by.

MK1 · « **Reply #7 on:** August 07, 2006, 11:10:24 PM »

It is possible that an oil gallery has been blocked when the engine was rebuilt. This could be either by an ill fitting gasket, sealant or the galleries in components not matched.

It could be that the tappets are not 'charged'. Take the rocker box off and run the engine, you should be able to see the valve action. You will however make a bloody mess.

Ric Jacques · « **Reply #8 on:** August 08, 2006, 08:35:03 AM »

Hi Henry - told you you'd get more CJ responses from Birtys! Welcome across!

Anyway seems you have a strange one. Has your rocker cover been replaced? The reason I ask is that I just replaced mine.......however some of the rockers were actually making contact with it. Had to identify which ones from the marks they made on the inside then beat it out a bit with a ball pein hammer, just enough to get some clearance.

If you have a spare distributor shaft you can pull the dizzie out and put the spare shaft in the hole, engage the oil pump drive, and spin the shaft with a drill. With your rocker cover off you will see if the oil is reaching the rockers without making such a bloody mess as you will if you run her with the cover off!

Mike Pavelin · « **Reply #9 on:** August 08, 2006, 09:01:05 AM »

Is the cam timing correct?

MK1 · « **Reply #10 on:** August 08, 2006, 09:11:38 AM »

Quote from: "Mike Pavelin"

Is the cam timing correct?

You'd struggle to get it wrong, it's just a matter of lining up the dots. (But you never know).

isle of man · « **Reply #11 on:** August 08, 2006, 09:12:53 AM »

Quote from: "henrycj5"

someone mentioned replacing the pcv valve? never heard of a pcv valve

"positive crank ventilation" basically it's a flame trap filter....if blocked the oil is normally pushed out of the rear main seal.

peter henry

elvis · « **Reply #12 on:** August 09, 2006, 10:54:01 PM »

spoke to bubba yesterday he asked if the engine was built with the head and rocker shaft and push rods from the same engine or was it built from two units he says the oiling is not the same on 73 to around 78 somthing about hollow pushrods and oil ways water pump was slightly diferent in the castings too very helpfull chap he sorted a problem for me at the same time

Anonymous · « **Reply #13 on:** August 10, 2006, 09:42:37 AM »

wow elvis.......you and bubba could be one :?

you have a very similar writing style

henrycj5 · « **Reply #14 on:** August 10, 2006, 10:04:36 AM »

Hi All,
The engine (head & block) are from the same unit and have never been swapped.
Any of you guys local to me (Thorpe, Surrey) would be nice if I could show it to one of you.

Thanks

Henry

MK1 · « **Reply #15 on:** August 10, 2006, 10:30:57 AM »

Quote from: "She Devil"

wow elvis.......you and bubba could be one :?

You never see them together in the same place. :thinking:

Anonymous · « **Reply #16 on:** August 10, 2006, 10:37:47 AM »

It certainly is a mystery :-k

Bubba · « **Reply #17 on:** August 10, 2006, 08:57:20 PM »

ha ha ha that is funny but wrong

eastryjeep · « **Reply #18 on:** August 31, 2006, 01:19:34 AM »

Are you sorted yet, or still battling?
You don't say which engine you have, is it the 6/232 (3.8 litre) or the 6/258 (4.2).
The fact that you say you have a top end rattle confuses me as the cam followers are in the block, more or less behind the distributor. So I would probably rule them out as the source of only a minor rattle, a heavy hammering is what you get when they fail, it's so bad I thought I'd run a bearing when it happened me!
You said that this was the second rebuild, if you've had the head and block skimmed on both occasions it might be worth checking that you are still within tolerance for the pushrods you are using.
Did you install valve seat inserts that are perhaps not machined to the correct height in one of these rebuilds? Just need to find out if any of the followers are bottoming out for some reason, you don't have some wild cam in there do you?
Hope you are already fixed up or that this helps, Have rebuilt my 6/258 umpteen times now so give me a yell if you need any more gloom on what can go wrong on these simple but bullit-proof engines!

henrycj5 · « **Reply #19 on:** August 31, 2006, 10:34:33 AM »

thanks for all the info sounds like you know what your on about. The rattling sounds just like my ol' grannies sewing machine. I've just left the jeep with an american car specialist who also seems to know his stuff.

I will definetely pass your comments on although he has just given me one of the lifters which he thinks are incorrect. (too short) So I'm off to my US car parts firm to check and compare to ensure they have given me the right one.

Oh my inline 6 is a 258, (I think)

eastryjeep · « **Reply #20 on:** August 31, 2006, 02:56:19 PM »

You might also ask your man to hot dip the block and crank before reassembling, this will ensure that any crud is washed out of the oil ways. Many machine shops often intentionally block the oil passages with wax before starting work to keep swarf and grit out, but it wouldn't be the first time they forgot to remove all their plugs! The hot dip gets all that out plus any odd bits of fluff left by rags, scraped knuckles etc.
Does your engine backfire through the carb by any chance?
What carb do you have fitted and what distributor type, (points, electronic or hybrid; ie 'Lumenition' or similar), as the different cam profiles for the mechanical advance systems may cause your engine to over-advance. I mention this as I had endless problems when I first fitted headers to my 6/258 and wondered if you had done your engine mods incrementally or all in one big hit.
What I'm getting at is that the vacuum through the carb throat and vac. advance need to be within specified parameters or you just get next to nowhere with high fuel consumption and very little power.
Once upon a time, I had a competition distributor and a Webber 38 DGAS carb fitted and running nicely, I then broke the cast exhaust manifold and replaced it with a set of headers, & that was where the problems started. The long and short of it was that the increased air flow and reduced inlet manifold pressure unbalanced the air fuel mixture and caused the distributor to over-advance the ignition so much that the engine only ran on full choke and then died when the automatic choke cut out! It also sounded like a bag of nails and couldn't pull the skin off a rice pudding. I eventually had to ditch that distributor and go back to the stock Motorola set-up and get the carb seriously re-jetted, took a day on a rolling road before my mechanic was happy enough to let it go!

henrycj5 · « **Reply #21 on:** August 31, 2006, 05:53:42 PM »

More notes for the mechanic.. excellent.

The engine was rebuilt once about 8 years ago but sat in my garage before I finally completed the restoration job. Everything was stock and when we first got it running it didn't run right and had a similiar tapping sound as to what it has right now. The oil pump then packed up whilst driving and a lot of damage was done to the bottom end.

I have then had the engine rebuilt again.. early this year and whilst waiting for the engine to be rebuilt by the local mechanic (I regret now not taking it to someone will real experience) anyway whilst it was being finished I went shopping in the US and brought myself exhaust headers, a performance inlet manifold and a 4br Holley.

The local mechaninc could not set up the timing that well and didn't know his way around a holley carb either. So I have been driving with terrible fuel ecomomy and a nasty tapping/rattling from the engine for a few months.

Anyway to finish the essay, I now have an American Car specialist looking at the engine. He immediately set the carb and timing in a matter of seconds giving the Jeep loads more power!!! He is now looking into getting to the bottom of the rattle which he believes are being caused by incorrect lifters! (apparently they are not long enough according to him)

But all your suggestions sound very interesting so I will be passing them on asap! Many thanks, Henry

isle of man · « **Reply #22 on:** August 31, 2006, 06:01:44 PM »

surly the lifers must be to long?

??because if too short the sound would be more like pinking.

peter henry

eastryjeep · « **Reply #23 on:** September 01, 2006, 12:31:54 PM »

Why not phone the guys at Lighthouse Jeep (01953 681237) and ask what part number lifter should be in there? Your original mechanic should be able to tell you what he ordered last time round from his paperwork, he has to keep records for tax purposes I think, so should have a record, compare numbers and 'Hey presto', an answer! Then again if the original mechanic is not VAT registered then he'll have binned the lot but isn't that naughty in itself, I wouldn't call it revenge if you didn't shop him to HMG Customs, but it might encourage him to be helpful!

eastryjeep · « **Reply #24 on:** September 01, 2006, 01:39:13 PM »

Whilst I think about it!
Back in the dark days of history I installed a simple mod which anyone who doesn't want to risk a siezed motor can do!

Install a brass or steel Tee piece and pressure switch, either before or inline with, the oil pressure sender, then wire it in or have it done by a pro, so that if the oil pressure drops the feed to the ignition is cut!

I don't consider it a down side, but it does mean that the engine won't fire on start-up until it's got sufficient oil pressure, so your battery does need to be in reasonable condition. Just make sure your sparky tells you how to over-ride the mod incase you ever need a jump start, and then replace when you have a nice healthy battery again.

This also has the added advantages of protecting you from upset bank managers, the wrath of her indoors and could even be considered cheap wallet insurance!

As ever, all vehicle modifications are done at your own risk.

Author Topic: 74 CJ-5 engine trouble.... please help (Read 11933 times)

henrycj5

Anonymous

henrycj5

henrycj5

Anonymous

MK1

Ric Jacques

Mike Pavelin

MK1

elvis

Anonymous

henrycj5

MK1

Anonymous

eastryjeep

henrycj5

eastryjeep

henrycj5

eastryjeep

eastryjeep