engine knock on a '74 eldorado 500

["Cadillac Kid" Greg Surfas 15364]

All,
Attached is a shot of a couple of cams for reference.  Please notice that the #1 bearing actually butts up to the cam gear attaching flange and the flange has essentially a ring of "thrust bearing". Also note the distributor drive gear that is an integral part of the cam casting (or in this case forging).  Think about what happens if the cam moves back and forth.  The distributor gear which also drives the oil pump is forced back and forth, and the thrust bearing on the flange does not do its job smoothly.
Just saying
Greg Surfas

[Cadillac Fleetwood]

I seem to recall reading a Cadillac service publication  from the 1970's (The Cadillac Serviceman, perhaps), in which a knocking sound that appeared to come from low in the engine was diagnosed. The article mentioned that one of the water pump attachment bolts, the one nearest the fuel pump, was a fraction too long, and because of the excess length, the fuel pump lever was striking it, creating a rhythmic, low-engine knock.  The test was to back out the bolt nearest the fuel pump, and run the engine.  If the knock disappeared, the remedy was to replace the bolt with a shorter one.

-Charles Fares

[TJ Hopland]

Interesting tidbit.    I'm gonna go check a fuel pump I pulled off due to knocking to see if there are any scratches on the arm.   New pump is worse.  No pump its quiet.

[Glen]

I seem to recall reading a Cadillac service publication  from the 1970's (The Cadillac Serviceman, perhaps), in which a knocking sound that appeared to come from low in the engine was diagnosed. The article mentioned that one of the water pump attachment bolts, the one nearest the fuel pump, was a fraction too long, and because of the excess length, the fuel pump lever was striking it, creating a rhythmic, low-engine knock.  The test was to back out the bolt nearest the fuel pump, and run the engine.  If the knock disappeared, the remedy was to replace the bolt with a shorter one.

-Charles Fares

That’s in the 1970 Cadillac Serviceman page 50 (November)     

[andysarcade]

ok, i took the car to Greg in Campbell CA to see what he thinks.

He's mystified by the noise too, never heard such a thing before and cannot pinpoint it but thinks several things are going on.

Being able to move the camshaft he says is not a problem looking at how it sits under the timing cover?

He things there is Rod Knock, the noise changes when plug wire is pulled on #7 cylinder :\

The flywheel is also cracked...

He's suggesting an engine replacement as rectifying the existing problem is a big job anyhow, we're not sure that whoever rebuilt it did things properly, so the engine is going to need a tear down to inspect everything - so a full rebuild is on the cards in other words.

He's got two replacement engine options, but one is a 1970 Eldo and known good (but has heater hose problems mating back up?), the other has sat for 20 years and is from a sedan - but of course would require a bunch of work to get going again.

I'm at an impasse on what to do - rebuild this engine? Neither of the replacement options sound ideal.

[The Tassie Devil(le)]

G'day Andrew,

Opening up an engine to correct "known" faults is like opening a can of worms, as once opened, the chances of finding a simple remedy is nigh-on impossible.

Me, I would be replacing the engine with the 1970 engine, so long as it is a good engine, and benefiting from the increase in power.   BUT, in your case, where you could be subject to pollution inspections, a change of engine might be thought to be wrong by the authorities.   The earlier engines didn't have the anti-pollution stuff as the later ones.

BUT, knowing there is a cracked Flex Plate, and a possible bearing gone, I would also be stripping the engine down to investigate, and consider repair, depending on what is found, if you want to retain originality.

If you decide to use the Sedan engine, make sure that you transpose the dip stick tubes to the Eldorado position, as there is a difference.

Bruce.

[andysarcade]

Thanks Bruce,

Fortunately 1974 (my year) doesn't need any kind of smog or inspection, i can do what i want to it... Is the 1970 engine a fit? The guy was telling me something about heater hoses not being the same so cannot swap in?! I would lean toward the 1970 engine as its a known worker (allegedly).

But i hear you on the other issues my engine may have. I would like to keep it original, but i don't particularly fancy financially supporting a can of worms if getting my engine stripped turned into that.

I'm prepared to sink money into the 'right' solution to make this a nice reliable driver. I don't want to put in something that develops a host of new problems, and the thought of putting in a 472 sedan engine thats sat outside for 20 years - even with a full going through - doesn't fill me with confidence.

I will consider the 1970 engine perhaps... Then i may get my own engine put on a stand and see about getting it investiagted... if its fixable then it could be fixed and sold perhaps if thats economical..

G'day Andrew,

Opening up an engine to correct "known" faults is like opening a can of worms, as once opened, the chances of finding a simple remedy is nigh-on impossible.

Me, I would be replacing the engine with the 1970 engine, so long as it is a good engine, and benefiting from the increase in power.   BUT, in your case, where you could be subject to pollution inspections, a change of engine might be thought to be wrong by the authorities.   The earlier engines didn't have the anti-pollution stuff as the later ones.

BUT, knowing there is a cracked Flex Plate, and a possible bearing gone, I would also be stripping the engine down to investigate, and consider repair, depending on what is found, if you want to retain originality.

If you decide to use the Sedan engine, make sure that you transpose the dip stick tubes to the Eldorado position, as there is a difference.

Bruce.

[The Tassie Devil(le)]

Andrew,

The heater hose in my '72 plumbs into a large hole at the rear of the right cylinder head, so yours would probably be the same.

If the '70 engine doesn't have this feature, extending the hose to the next port shouldn't create a major problem.

Bruce.

[chrisntam]

Why not rebuild the existing engine, or at least tear it down for an evaluation?  Isn't the car worth more with the original (born with) engine?

If you go with the '70 engine and rebuild it, consider lowering the compression as the factory rating is advertised as 10:1, from what I understand, it's actually closer to 9.3:1.

I had mine rebuilt and it's now a true 10:1, but I have to run 93 octane in it all the time.  That's my only regret on the rebuild, I should have lowered the compression for regular ol' pump gas that is available anywhere.  93 is available here in Dallas, but may not be as readily available on future road trips.

Iffin it were me, I'd rebuild the original, unless, after tear down, it's not useable.

[The Tassie Devil(le)]

I rebuilt my engine to '70 Specks as far as the compression went, but I use an octane booster to control the pre-ignition.

Can't get good exhaust note out of a low compression engine.

Bruce.

[Jeff Rosansky CLC #28373]

Just my opinion.
Either way your engine has to come out. Spend a few hundred to have yours looked at. True, you may be opening a can of worms but at least you will know. If it is a can of worms then stop and go with the other option.
Just my opinion, and best of luck.

Does your engine guy know this engine? Do your research as a bad rebuild really sucks.
Jeff

["Cadillac Kid" Greg Surfas 15364]

Andrew,
All other discussion aside, Neither of the two replacement options sounds good to me.  Removal and replacement of your engine should run somewhere between $1500 and $2000.  Rebuilding your motor including boring the cylinders and replacing rings, bearings, camshaft, lifters, oil pump should (including the California factor) around $3,000.
Big hit, but if replacement is necessary you will hopefully get some warrantee and a car that will be good for years.
Greg Surfas

[andysarcade]

Thanks for the price guide there. Just to clarify, removal and replacement of the engine is 2k, and the rebuild is 3k, so i should expect 5k total?

A third option has cropped up.. a whole donor car (a 73 eldo) with a good engine for $1500.  Its low mileage (69k) and appears in very decent non-rusty california-shape. I'm hoping to go look at it on monday. Its scrappy looking on the outside, so its a perfect engine donor i think.

I would like to stick with rebuilding the original engine if i can, but i've been warned against that. Sure, if i could have it stripped down to find the problem cheaply then great, but i think thats an expensive prospect.

Question: to replace  the flywheel do you have to pull the engine out anyway? Its starting to sound like no matter what course i choose, pulling the engine needs to happen.

Jeff Rose : if i could have my engine pulled and looked at for a couple hundred i would have done that! The guy with the car right now is a Cadillac specialist with 30+ years in the game. He's not an engine specialist, just caddy cars in general. If i could find an engine specialist i would have it sent out to be properly done, i need to investigate whats nearer to me to to maybe have this done - If i dont go with the '73 engine swap...

Andrew,
All other discussion aside, Neither of the two replacement options sounds good to me.  Removal and replacement of your engine should run somewhere between $1500 and $2000.  Rebuilding your motor including boring the cylinders and replacing rings, bearings, camshaft, lifters, oil pump should (including the California factor) around $3,000.
Big hit, but if replacement is necessary you will hopefully get some warrantee and a car that will be good for years.
Greg Surfas

[The Tassie Devil(le)]

The engine has to be separated from the transmission completely, and once that far, it is a simple task to remove it to access the Flex Plate.

A word of warning.   Don't get a Flex Plate that has been made in either Mexico or China, as I suffered from that problem when teeth came off the flex plate, and it turned out that when comparing the original to the replacement, they were slightly different in diameter, and a lot different in ring gear spacing.

I ended up with my machinist removing the ring gear and replacing it in the correct position, and welding it back on in such a way that the teeth remained square, and not pulled to one side due to incorrect welding.   I have pictures if you are interested.

Bruce.

[Jeff Rosansky CLC #28373]

Jeff Rose : if i could have my engine pulled and looked at for a couple hundred i would have done that!

Sorry if I was unclear. Either way your engine is coming out so no matter what you are spending that $$. My point was that if it was out anyway spend a bit and have it really looked at at that time.
You are talking about replacement options without really knowing what is going on with yours so it would be worth dropping the pan, etc before you commit to another option.
I know it costs more than  couple hundred to pull and inspect an engine.
Sorry for the confusion.
Jeff

["Cadillac Kid" Greg Surfas 15364]

Andrew,
I might suggest you call Jeff Nielsen director of the Northern CA CLC.  Perhaps he can give you some direction as fa as knowledgeable people in your area that can help you solve your "dilemma"

Jeff Nielsen
(650) 740-5204
jnielsen2219email addresses not permitted
Greg Surfas

[andysarcade]

Thanks for the pointers people...

The mechanic is sure there is rod knock going on right now in cyl 7, and maybe other things too. My transmission was also not super smooth in power take up or down either.. which leads me to this other solution..

I found a really good low miles (but ugly) '73 eldo coupe with a very sweet running engine and trans. For the price, and the convenience, I bought the car and we are going to do a full engine/trans swap right in. Many added bonuses with sacrificing this coupe including the transfer of larger interior trim (seat rear plastics and armrest plastics) that i have been looking for for ages. New power steering box and pump was also needed as mine was grindy and leaking. The AC compressor and climate system was also converted to R134A as was all working too where mine was needing total rework as it was seized/bad and was still R12. Also manual-fill rear air shocks i can pass over too.

The coupe vinyl roof had been skinned flat and it had a repaint which was peeling. The interior is a kind of weird metallic green, is in fantastic shape, but the colour clash with the outside (a blue-grey) is pretty horrendous. Many cosmetic flaws and a drooping rear bumper (not sure why) just means this was a mechanically good ugly duckling that i don't feel too bad for parting out. I drove it 15 miles through the mountains and it drove like a champ.

So, does anyone need a 500 engine/eldo trans with lower knock?

["Cadillac Kid" Greg Surfas 15364]

Sounds like you have your problem solved.
Greg Surfas

[andysarcade]

Sounds like you have your problem solved.
Greg Surfas

Famous last words!

Much hand-wringing and weighing of all the pros and cons has taken place that are too detailed for a forum post without boring everyone to bits.  Financially it makes sense to go down this road and not deal with a potentially bad block in the original engine. (which - by the way does not seem to be the factory fit engine anyway - numbers don't match - shouldn't the block have the last 6 digits of the VIN stamped on it? )

thanks