mkent

I picked up the LT4 extreme duty timing set from Dal last weekend and realized I need to order a new water pump driveshaft assembly. When searching the part number for that I came across a number of terrifying threads about the water pump drive gear and cam sprockets being chewed up after installation. I've got a ton of money in the bottom end to handle RealQuick's turbo setup so I'd rather not have gear teeth swimming through my oil system!
I'm running a stock GM water pump which was in good working order when I pulled it off.

Does anyone know the true common factor in these gear failures? Is it user error or manufacturing flaw? I found threads on the vette forums ranging back as far as 2004 with the same problem.

Some people have ran the LT4 ED cam sprocket with the stock LT1 water pump gear and had no problems, while others had failure. Some people pressed the new LT4 ED water pump gear on the drive assembly and ran it with the LT4 ED cam sprocket and also failed, yet others got away with it. Something seems fishy here and I don't know if its worth the risk to me. It seems almost like running the stock setup would have been better.

Walkersteelhead

I have decided to go with the stock setup.

2QUIK6

I'm sure you saw some of my info in those threads.... I'm on the fence, but alot of those failures had to do with them changing the waterpump while it was off...getting a Bosch wp at the local store..which had extremely tight bearings. I know the first one I got I couldn't even turn the shaft with my hand and it should turn smoothly and fairly easily by hand....Bosch had a recall on those a few years ago, but those that were on the store shelves got sold or remain there today to be sold. It doesn't take that much force to turn even with fluid behind it, defineitely not enough to strip teeth on hardened gears.
Also, be certain that the oil galley plugs right behind the cam gear are not plugged, this may have been another reason for failure as they supply oil to the gear teetI did not know this until recently or I would have checked mine..

After mine had a grinding noise with the stock wp gear with the ED set, I swapped it with an entire wp bearing assembly with the right wp gear on it and have put 10k miles on it without any further problems.....will be taking it apart soon for a cam swap though and will evaluate it again then.

multicar

<<Also, be certain that the oil galley plugs right behind the cam gear are not plugged, this may have been another reason for failure as they supply oil to the gear teetI did not know this until recently or I would have checked mine..
>>

I beleive the oil galley plugs are unique to a LT1/4 SBC. If your builder uses the standard SBC plugs(which dont have the oil hole) you will evenually chew up the cam timing gear. Of course if you decide to use an electric WP, this is a non-issue unless somebody puts a stock WP on it. Better safe then sorry, check with your builder for sure.
Doug

afr lt1

I think that is the same one I used, but I left the stock water pump gear on....i think. Absolutely no probs after 15k.

wrd1972

+1.
I am running this timing set on my new engine. I also checked the lash of the water pump gear and the cam sprocket to ensure they were not to tight.

Joe B

As long as the water pump isn't excessivly tight(like mentioned)....and you make sure to use the hardened water pump drive gear that comes with the ED timing chain set(and press it on to the right depth).......things should be fine........I've personally been putting those exact chain set's on dozens of LT1's over the years (my own stuff and others) and have never had an issue.......and if your still worried, mabe go with an electric WP so theres nothing at all to worry about(timing set wise)..............Joe

1racerdude

As has been stated make sure the .036 holes are in the oil galley plugs and they are not stopped up. Make sure you change the entire set at one time, don't just put part of it in and expect it to live.
The ED set is a Cloyes made for GM and to GM's spect.

mkent

Does anybody have a picture of these oil galley plugs? I'm willing to bet my builder put standard sbc plugs back in it. Also, if they did put standard plugs in my LT1, can I just drill a small hole in these plugs or must I have LT1 plugs put in it with the .036 hole already drilled?

1racerdude

They are small freeze plugs (3) that are behind the cam timing gear.
Yes you can drill them just put some grease on the bit to catch the shavings and don't force the bit through,just let it cut.
Drill only the left and right plugs leave the top/center alone.

mkent

Do I need to be precise with the .036" measurement or is bigger better for more oil flow?
I'm going to go check out the plugs right now and see what's up.
Also, should I just buy the water pump drive assembly with the hardened gear on it or should I buy the regular assembly and have the WP gear from my LT4 ED kit pressed on? I thought I read in one of those posts that there are 2 seperate part numbers for the WP drive assembly, one with the softer gear, and one with the harder gear.

1racerdude

Ya need to stay between .035 and .040 too big and ya will loose oil pressure.
I would call Cloyes and they can fill ya in on all the different pieces.

2QUIK6

The entire LT4 ED gear assembly (gear, shaft, retainer, and bearing) is part# 12551727 and my local dealer matched gmpartsdirect price for $62.
The stocker assembly listed for '95 was part#10219554 which was $51.

And here's a pic showing the tiny holes in the galley plugs

djk19

GO ELECTRIC!!! WHAT ARE YOU WAITING FOR PROBLEM SOLVED!!! If you have serious money involved then get serious and know that electric motors are efficient enough now to run the water pump at a constant 30+ gpm which is better then stock because at idle you are pushing 5 gpm and wot 50 somthing. It is better to either have a constnt 35+ - 50+ with a heavy duty unit then to even deal with the horseshyt stock setup we have. Take advantage of modern technology please. for us.

LiENUS

Why is it better to have a constant 35 gpm then to have 50 gpm? the stock setup is remarkably efficient, and it does one of the most important things a water pump should do, increase the work done as the workload goes up.