Broken camshaft bearing caps and rocker arm

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ontheebrink
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Broken camshaft bearing caps and rocker arm

Post by ontheebrink »

I broke 3 camshaft bearing caps and a rocker arm on my 91 L300. I jumped the timing while replacing the head gasket. Can I just replace them or do I need to replace the whole head? I'm getting mixed messages on various forums.
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Growlerbearnz
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Broken camshaft bearing caps and rocker arm

Post by Growlerbearnz »

Stink! The rockers are supposed to break first to save the cam and caps. What a mess. :-(

Unfortunately, it's more practical to replace the entire head. I would look for one that comes complete with cam, valves, and rocker gear.

You can't buy cam bearing caps separately. They act as cam bearings, and they have to line up perfectly with the camshaft. During manufacture the raw cam caps are bolted in place and the cam journals all bored at once and in line, so each cam cap is unique to its position on its head. It's possible, if you had a large enough collection of spare caps, you might find 3 that line up adequately, but I still wouldn't trust it.

You *can* just replace rocker arms, they're interchangeable. After a rocker arm breakage it's a good idea to replace the rocker shaft too.

I always turn the engine over by hand (socket on the crank pulley) a couple of times before using the starter, just in case this sort of thing is waiting to happen. :-(
Nothing says "poor workmanship" more than wrinkles in the duct tape.
ontheebrink
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Broken camshaft bearing caps and rocker arm

Post by ontheebrink »

Damn, I figured.

From what I can tell the 1991 has the protruding valve, is that correct? Do you know of any semi reputable places where I can order one. It seems a lot of people are complaining about cheap Chinese made ones. I'm seeing price ranges from $250-$1000. That seems a bit suspect to me.
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Growlerbearnz
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Broken camshaft bearing caps and rocker arm

Post by Growlerbearnz »

It should be protruding valve type but pull it off and check before you order, just in case someone's replaced the engine at some stage.

I'm not sure where to buy cylinder heads from in the US. My last cylinder head was made by AMC (an Italian company) and was decent quality but you're right- the Chinese ones have a bad reputation. At least, *some* of them do, and it's hard to know whether you're ordering a good quality head, or a cheap head that's been overpriced.

The usual "ordering from China" tricks apply, I guess; look at how many they've sold, how long the company's been in business, read the feedback. Watch out for companies selling second hand parts.
Nothing says "poor workmanship" more than wrinkles in the duct tape.
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joebillhill
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Broken camshaft bearing caps and rocker arm

Post by joebillhill »

I ordered a bare cylinder head from Quantico in May. Had a valve job done on it and moved the old rocker over as it was still relatively new.
Pretty damn cheap for the head (bare or assembled) free shipping, and good reviews of the company. Also it was one of the only protruding valves i could find relatively local. The mechanic said the casting looked good on the head when he took a look at it so here's hoping.
Also, you probably know, but get the right head gasket.
Not too big of a deal but i looked up the wrong one when shopping for a replacement viewtopic.php?f=6&t=18882
ontheebrink
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Broken camshaft bearing caps and rocker arm

Post by ontheebrink »

Quantico Cylinder Heads does make an assembled head. It comes with a one year warranty as well which I guess is good. They aren't based in the US though. I've had them mess up on a shipment and the part was actually shipped from England. The address on their website is a u-haul facility in Dallas and the guy who answers the phone isn't in Dallas, he's in Miami and it's a cell phone. Isn't the internet awesome?

https://www.qcylinderheads.com/collecti ... ubishi-max
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