Bob Dillon REPAIRS failed UIM'* to be the best solution in my opinion, especially when paired with Bill Buttermore'* reduced diameter stovepipe, aluminum framed lower intake manifold gaskets, and getting rid of the Dex-Cool. The lowers fail because of the Dex.

Bob and Bill are both Gearheads here. I just did the whole top end on EK98'* car last month, and his total costs were UNDER $200.

There'* more information in Techinfo, as well as numerous posts.

http://www.bonnevilleclub.com/forum/...e=article&k=38

http://www.bonnevilleclub.com/forum/...light=ek98+uim
(this took me 2.5 hours the second day by myself after a new OEM coolant elbow failed)

You can also sleeve your own upper if you like. If you want to buy a new upper intake manifold, I recommend the APN factory-sleeved upper. It will come with a reduced diameter stovepipe that will replace the stock pipe in your '98. Aluminum lower intake gaskets come from the dealer. The details are in the Techinfo article 38 willwren linked for you, above.

You will have to do this work sooner or later, and much better to do it before the bearings are damaged.

The wisp of steam at the front of the car could be a seep or pinhole leak in your radiator. To confirm this, have a cooling system pressure test performed.

Your help is very much appreciated. I have gone from thinking abou selling my car to looking forward to making the fix with the improvements.

Outstanding feedback.

Thank you so much. I'll let you know how it goes.

BF

I have been researching what all is involved in fixing the EGR stove pipe design problem, and replacement of the LIM gaskets.

One question I have is the Tech article #38 states that it makes sense to replace the "Coolant Bypass Elbow". What is that, and where is the best place to obtain one? The article says GM has the elbow, but I was just wondering.

I have a factory service manual due to arrive any day, so hopefully I will have the detail that I am missing.

Also, I think I will go with Bill Buttermore'* suggestion to buy the APN manifold and kit. Sounds like everything is there to replace the UIM. I will also buy the LIM gaskets and pull it too.

Do you need to pull the LIM to replace the stove pipe? One article seems to imply that you do, while APN info seems to indicate that you do not.

In this picture, the coolant elbow is the right side of the red lines. It comes out of the lower intake manifold and goes into the tensioner assembly.



The EGR stove pipe comes out the top of the LIM, so no the lower does not have to be removed to replace it. You do need to pull the lower intake manifold to replace its gasket which is strongly recommended.

Its possible they never changed the lower gaskets and now they are failing.

Very possible.

Well, its been over a month now since I completed the job and I thought I owed you all a report.

I fixed 4 things, and caused 3 problems.

Fixes:
1. Replaced leaking UIM with the APN kit. Great kit!
2. Replaced LIM gaskets
3. Eliminated sticking lifter noise while cold
4. Eliminated miss-fire by having fuel injectors rebuilt

Created 3 problems:
1. Serpentine belts screamed (figure I got coolant on the 1 yr old belt)
2. Puff of smoke out exhaust when engine started
3. Fast idle, 4 trouble codes.

I just about fired myself and sold my tools.

But have since fixed the 3 problems:
1. STP belt treatment for serpentine
2. Forgot to install PCV in UIM, and had added SeaFoam to oil to lube/clean the lifters. I thought I destroyed my valve stem seals! So either the Sea Foam burnt away or the missing PCV was allowing crankcase fumes in the combustion chambers.
3. Putting the PCV in fixed the fast idle, and stopped the 4 trouble codes.

So all is well. Thx to you fine folks for leading me through this. Again, 5 stars on the APN kit!

BTW, doesn't someone here want the old UIM to make mailboxes, or to refurbish them?
2.

Send a PM to Bob Dillon about the UIM. He may want it.

The PCV bites a few people. But the puff of white smoke at startup concerns me. That'* an indication you may still have a leak.

The puff of smoke appears to have ceased. Also, the coolant level has not dropped at all.

So I am thinking that it was coming from either the crankcase fumes being directly sucked into the manifold, or else the Sea Foam oil additive was finally burnt off (it is like Marvin'* Mystery Oil, with the viscosity almost of water). I lost more than a quart of oil during the first 1000 miles but that is not happening anymore either.

I will keep an eye on it but it was quite obvious.

At this point, zero coolant loss and no oil level loss.