'89 C2500 TBI 5.7L oiling problem - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 04-28-2010, 12:28 PM
Registered User
 
Join Date: Apr 2010
Location: Washington state
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
'89 C2500 TBI 5.7L oiling problem

My '89 C2500 is showing some weird symptoms since installing a freshly rebuilt 5.7L. The engine is bored .060 over and has a RV cam (designed for TBI) other than that it is a stock engine.

This is my main concern

1. At idle the oil pressure drops to zero as indicated on the gauge- it happens anytime the oil pressure drops to 15 psi or below. It acts just like the gauge is losing power- instant drop and the check gauges light comes on. This worries me but I must still have oil pressure since the engine makes NO noises like failing lifters or knocking AND the fuel pump keeps running. The sender up by the distributor should shut off the fuel pump if the pressure truly drops to zero (I've tested the sender and it is working). I'm installing a direct mechanical oil pressure gauge today to verify oil pressure, I'll post again this afternoon with the results. So.... does anyone have any ideas? I'm pretty well stuck.

update: I just finished installing a mechanical oil pressure gauge to verify that I do, in fact, have oil pressure (I was thinking that the factory gauge/ sender might be wonky). Unfortunately, my oil pressure on cold start is in the 30-35 psi and drops off to zero as the engine warms up... I used this high volume oil pump in my build:

http://www.cpperformance.com/detail.aspx?ID=9381

I installed a new crankshaft, new bearings, plasti-gaged every bearing and they were right in the middle of the spec. I had a buddy working with me on the build, we double-checked each others work, so I know the clearances are good. Anyone got an idea on what could be causing this?!?

minor problem at this point

2. After cold start up and then warming the engine up, it has a stumble on acceleration (if it were carb'ed I'd describe it as if the accel. pump wasn't working). I read the codes and found a code 33 set (MAP sensor). I tested the MAP sensor and it was bad so I replace it yesterday afternoon and took it for a drive. No change in the problem.

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-28-2010, 01:16 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,947
Wiki Edits: 0

Thanks: 4
Thanked 480 Times in 410 Posts
Quote:
Originally Posted by Trainwreck
My '89 C2500 is showing some weird symptoms since installing a freshly rebuilt 5.7L. The engine is bored .060 over and has a RV cam (designed for TBI) other than that it is a stock engine.

This is my main concern

1. At idle the oil pressure drops to zero as indicated on the gauge- it happens anytime the oil pressure drops to 15 psi or below. It acts just like the gauge is losing power- instant drop and the check gauges light comes on. This worries me but I must still have oil pressure since the engine makes NO noises like failing lifters or knocking AND the fuel pump keeps running. The sender up by the distributor should shut off the fuel pump if the pressure truly drops to zero (I've tested the sender and it is working). I'm installing a direct mechanical oil pressure gauge today to verify oil pressure, I'll post again this afternoon with the results. So.... does anyone have any ideas? I'm pretty well stuck.

update: I just finished installing a mechanical oil pressure gauge to verify that I do, in fact, have oil pressure (I was thinking that the factory gauge/ sender might be wonky). Unfortunately, my oil pressure on cold start is in the 30-35 psi and drops off to zero as the engine warms up... I used this high volume oil pump in my build:

http://www.cpperformance.com/detail.aspx?ID=9381

I installed a new crankshaft, new bearings, plasti-gaged every bearing and they were right in the middle of the spec. I had a buddy working with me on the build, we double-checked each others work, so I know the clearances are good. Anyone got an idea on what could be causing this?!?

minor problem at this point

2. After cold start up and then warming the engine up, it has a stumble on acceleration (if it were carb'ed I'd describe it as if the accel. pump wasn't working). I read the codes and found a code 33 set (MAP sensor). I tested the MAP sensor and it was bad so I replace it yesterday afternoon and took it for a drive. No change in the problem.
TBI is real sensitive to the cam whether that's a contributor to the problem would take knowing its specs. Check the manifold vacuum, TBI doesn't like low vacuum which comes with more camshaft.

The stumble on warmed acceleration is typical of the cam being incompatible with the fuel and ignition maps in the computer. What you feel is the mixture going lean when the computer takes the fuel off cold start rich (choke) and goes into closed loop operation thru the O2 sensor. You can trick the system by lowering the engines operating temp so it doesn't get above 170 degrees so the computer will stay in open loop operation which also keeps the mixture in the rich (choke) operation. This isn't a permanent fix as the engine sees faster wear at these low operating temps and the rich mixture washes lube off the upper cylinder walls. Another temp fix is to install an adjustable regulator into the TBI. This lets you richen up the mixture by raising the fuel pressure. The best fix is a new PROM chip with a new program that realigns the cams effect on manifold pressure (vacuum) with the fuel and ignition maps. Not a cheap solution up front but for a long engine life the most effective. Simple hot rod chips don't do it, this needs to be from a custom house like these:

http://www.fastchip.com/

http://www.tbichips.com/

http://www.hypertech-inc.com/ look under power chips



Bogie
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-28-2010, 01:38 PM
Registered User
 
Join Date: Apr 2010
Location: Washington state
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
The cam I used was specifically chosen for its compatibility and its past record with the stock TBI system. My fuel pressure is 12.7 psi which is more than adequate for the truck in its present configuration. It is possible that the cam may contribute to some of the stumble but I doubt it, as it is a cam grind that has been used by myself and a couple of other local guys in their TBI engines in the past) and, as I said in my post, I'm more concerned with the oil pressure issue right now. Thanks for your input though, I do appreciate it
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-28-2010, 03:17 PM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
A high volume pump should not have been necessary, but that said- it should supply ample pressure if all's well otherwise. This includes being able to get the oil back into the pan from the top end, via the various drain backs. These are all fully operational- as in, not screened over or plugged intentionally to prevent "windage losses"?

If the pump's bypass has hung up, that can cause low pressure, or if the spring is incorrect, weak or broken.

The pick up can be loose, allowing air to be mixed into the oil. If the pump mounting surface (or the cap's surface) is uneven, or something was accidentally trapped under the pump, this can cause a loss of pressure. Same thing for the cover on the oil pump itself. Was the pump pulled apart, pre installation?

Obviously, the filter being plugged or too thin viscosity will cause a loss of pressure. The plug at the rear main reinstalled if it was removed for cleaning?

If the rearmost cam bearing was incorrectly installed, this will also cause pressure probs. If the distributor shaft is a loose fit, there can be pressure losses at the crossover point where the dist. body intersects the oil galley.

Last edited by cobalt327; 04-28-2010 at 03:25 PM.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-28-2010, 03:35 PM
Registered User
 
Join Date: Apr 2010
Location: Washington state
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Thanks Cobalt327, those are the things I've been going over in my head today. If I can't find anything external, I'll be pulling the pan and pump this weekend. Arrgh! This has been one of those problem child trucks. But when I'm done it will be SWEEET (gotta keep a positive attitude right?)
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-29-2010, 05:45 PM
Registered User
 
Join Date: Apr 2010
Location: Washington state
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I had some free time today and I decided to pull the pan off the engine and check to see if the passage underneath the rear main cap had the plug in it. I pulled the pan and oil pump then the rear main bearing cap. The plug IS in place and, after disassembling the pump (which looks perfect as it should), I noticed that the rear main bearing half in the cap is galled badly, although the journal on the crank still looks fine. I also found what looks like the remains of a small freeze plug in the bottom of the oil pan. So the motor is coming out on Sunday. I believe that one of the plugs under the timing cover blew out, we will see when it comes apart. I'm keeping my finger crossed that the crank is going to turn out ok. I'm sure that I'll be replacing the bearings......... crap. I'll post more after tear down.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 05-01-2010, 09:19 AM
Registered User
 
Join Date: Apr 2010
Location: Washington state
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
I got the tear down done yesterday afternoon. Not good at all, all three of the plugs under the timing cover blew out! One was found in the oil pan, one was still hanging in the hole (barely), and the third one was embedded in the crankshaft timing gear, between the rows of teeth. The crank has three of the main journals scored and all the main bearings are galled. Luckily the cam, lifters are ok. Crap! No more high volume pumps for me, gotta start gathering parts on Monday.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 05-01-2010, 09:31 AM
cobalt327's Avatar
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 597 Times in 546 Posts
Quote:
Originally Posted by Trainwreck
No more high volume pumps for me, gotta start gathering parts on Monday.
You might not need the HV pump, but this points to an incorrectly staked cup plug most likely, and/or excessive pressure- not the HV oil pump.

If the galley hole face is pretty beat up from previously staked plugs, you should go ahead and tap them for 1/4" NPT pipe plugs. When you do this, use sealer and plugs w/a female allen hex.

Last edited by cobalt327; 05-01-2010 at 10:24 AM.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 05-01-2010, 02:54 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,947
Wiki Edits: 0

Thanks: 4
Thanked 480 Times in 410 Posts
Quote:
Originally Posted by Trainwreck
I got the tear down done yesterday afternoon. Not good at all, all three of the plugs under the timing cover blew out! One was found in the oil pan, one was still hanging in the hole (barely), and the third one was embedded in the crankshaft timing gear, between the rows of teeth. The crank has three of the main journals scored and all the main bearings are galled. Luckily the cam, lifters are ok. Crap! No more high volume pumps for me, gotta start gathering parts on Monday.
That's a pressure not a volume problem. The pump's relief valve is either working against excessive spring pressure that delays its opening, or the valve is hung up on a burr or chip preventing its opening. This can happen on a regular pump with exactly the same result. Without a properly operating relief valve, a stock pump or a high volume pump, either one, can develop way more than enough pressure to blow out pressed in plugs or blow up the oil filter. This valve is always what controls ultimate system oil pressure, especially if the oil is cold. You can see this in how the pressures change with RPM between a cold and hot engine. When you first fire a cold engine, new or old the pressure goes very high. Without a relief valve the pump can easily generate 100 to 200 psi depending on RPM. Therefore, a relief valve is there to set an upper limit by opening a vent to the intake side of the pump. However, as the oil heats up it looses viscosity; only then does the pressure drop off and does so drastically. You can see this if you have a sensitive enough oil pressure gauge. When you fire up a cold SBC, at idle you'll see the pressure at 60-70 psi. If you rev the engine to cruising speed, the cold pressure will stay at 60-70 PSI, because this is where the relief valve is set to open and the cold thick oil is resistant to being pushed thru the bearing clearances, so the pressure you see on the gauge is where the relief valve is venting the excess oil back to its intake side. Later, once the engine has warmed, the oil the pressure will fall back to 50-60 psi at cruise RPMs, which shows the relief valve is no longer venting oil as the pressure is now below its opening point. When you return this hot engine to idle, the pressure will drop to 20-30 psi where it had been at 60-70psi when it was cold. These numbers also move around with oil weight whether straight or multi grade. A high volume pump tends to hold a higher hot pressure at idle because it's putting more oil into the system, so you might see 40-50 psi on a hot idle which tells you the relief valve is closed. The range of difference in pressure to RPMs between idle to cruise will be smaller as the typical 60-70 psi will arrive at a lower RPM as relief valve opens against the increased volume so this will reach the relief valve's pop off pressure at a lower RPM. The system should not see a higher max pressure unless the valve's closing spring was changed to one of greater force or the bypass is not sized adequately to deal with the increased volume coming out of the pump. This of course assumes normal production type bearing clearances. If you widen the clearances and or add things like indexed oil streams onto the bottom of the pistons to cool them or behind the cam gear thrust bearing, or additional oil to sprayers inside the rocker covers to cool the valve springs, or a lot of external plumbing for remote oil filters and coolers, because these additional duties will reduce engine oil pressure and volume, requiring a higher volume pump to make up the difference in oil demand and systemic losses to passage friction. But these are things mostly done on competition engines and are seldom seen in street vehicles. The other use for the high volume pump is to keep lower RPM pressure up under high crankshaft loading like towing at highway speeds. But one has to keep in mind that all this extra oil costs power to pump and is a drain-back management problem. This really requires a good windage tray, crank scraper and pan to get it out of being whipped up where the crank is loosing power just getting thru the oil fog and the rings are swimming in more oil than they can clear off the cylinder walls.

All three galley plugs being blown out would make one think none of them were installed adequately. Especially the lifter galley plugs as they see a lot less oil than the main galley because they are feeding the upper end thru the pushrods. This was either not a correct fit diameter wise, or not installed deeply enough, and probably not staked in place after installation. The press in plugs are usually replaced with screw in plugs and Loc-Tite for anything other than stock rebuilds. But one needs to pay attention to the depth of a screw in plug on the front of the main oil galley as too long or too deep will cut off oil to the number one main.

Bogie

Last edited by oldbogie; 05-01-2010 at 06:21 PM.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 05-01-2010, 05:20 PM
sbchevfreak's Avatar
Licenced Automotive Technician
 
Last photo:
Join Date: Feb 2004
Location: Land of big Easter eggs, Alberta
Age: 34
Posts: 1,609
Wiki Edits: 0

Thanks: 13
Thanked 9 Times in 9 Posts
Quote:
If the galley hole face is pretty beat up from previously staked plugs, you should go ahead and tap them for 1/4" NPT pipe plugs. When you do this, use sealer and plugs w/a female allen hex.
I recommend this with all builds. After seeing this several times, I find the added peace of mind of a pipe plug is more than worth the effort if the install.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 05-03-2010, 10:33 AM
Registered User
 
Join Date: Apr 2010
Location: Washington state
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by oldbogie
The other use for the high volume pump is to keep lower RPM pressure up under high crankshaft loading like towing at highway speeds.
Bogie
Which is exactly the purpose of this truck build. It will be hauling a cab-over camper and pulling an enclosed trailer behind full time. I've used almost this exact combination before and had zero problems (the previous build was carb'ed not TBI- otherwise the same recipe and parts were used). The oil plugs were not staked this time....... my bad. They will be staked this time I assure you, and I am dropping back to a standard oil pump. I will be adding a large external cooler, however, to provide additional cooling potential for the oil as well as increasing the volume of oil in the engine. We'll see how it goes.

I've read that the oil galley plugs are available in two different diameters, is there any truth to that?
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 05-20-2010, 06:13 PM
Registered User
 
Join Date: Apr 2010
Location: Washington state
Posts: 12
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Engine is back together and in truck and oil pressure is great! Thanks for all the help everyone!!
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
TBI 305 problem JohnyR17 Engine 5 06-02-2005 05:13 PM
'89 IROC wiring problem jmtw Electrical 8 12-31-2004 12:48 PM
Edelbrock TBI Manifold Problem? erichb Engine 4 12-06-2003 09:29 PM
tbi 350 oil pressure sending unit problem HELP orangebaja Engine 3 11-07-2003 07:23 PM
please help..... annoying warm start problem 67cuda Engine 21 03-28-2003 05:44 AM


All times are GMT -6. The time now is 04:43 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.