Same problem new motor.. - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TrueChevyTech · 01-06-2012, 10:35 PM

Yes the egr has a N, so negative back pressure it is. The numbers on the valve are "dcw 17087198 086 71N" it is 87 half ton 2wd , factory 305, previous owner did a 350 swap, it ran great for 4 years for me then after sitting a couple months it started stumbling slightly above idle. Moving or parked.
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ChevyTech · 01-06-2012, 11:43 PM

The EGR should not open at all without vacuum from the solenoid.

Sometimes the spring inside the EGR valve gets rusty and breaks.

It takes very little vacuum to move the EGR valve diaphragm.

Did you look at the link of the illustration to see there is a control mechanism inside the EGR valve? That mechanism is the common failure on these trucks. It has to modulate the opening of the valve.

A good test for these is to put a hand vacuum pump on the EGR valve and apply vacuum with the engine off and it should hold vacuum. Leaving the vacuum on it, start the engine, and the valve should close. If it stays open the EGR valve has an internal problem.

Look carefully at EGR number, there is a number 17087196 which is common.

ChevyTech · 01-07-2012, 12:13 AM

Do you have one open port on the EGR solenoid?

On a negative backpressure EGR solenoid there is one port which is the vent and should be left open but people find a spot they think should have a vacuum hose, so they plug the vent port. The vent port does not have barbs on it like the one that is supposed to go to the EGR valve.

TrueChevyTech · 01-07-2012, 12:20 AM

Yeah the numbers I posted are right. I quadruple checked
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TrueChevyTech · 01-07-2012, 12:24 AM

Yes I also replaced the solenoid, it wasn't holding vacuum very well, vent has filter, I squeezed egr then hooked vacuum gauge, it held at 5 inches (hardest I could squeeze) it also didn't bleed off on start and after warm up
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TrueChevyTech · 01-07-2012, 02:02 AM

After doing some research the EGR 17087198 would be factory for the 305 motor that was original for that truck. I'm wondering if I should change to a different EGR. This also makes me wonder if the TBI system is for the 305 as well but that would be a different thread

TrueChevyTech · 01-07-2012, 02:46 AM

update- I know the truck ran great before so I went ahead and ordered ACDELCO Part # 2145536

ChevyTech · 01-07-2012, 10:53 AM

Quote:

Yes I also replaced the solenoid, it wasn't holding vacuum very well, vent has filter, I squeezed egr then hooked vacuum gauge, it held at 5 inches (hardest I could squeeze) it also didn't bleed off on start and after warm up.

It did not bleed off, so your test shows a failed EGR valve.

Quote:

After doing some research the EGR 17087198 would be factory for the 305 motor that was original for that truck. I'm wondering if I should change to a different EGR. This also makes me wonder if the TBI system is for the 305 as well but that would be a different thread.

I have seen the same EGR valves used on different size engines. If the EGR parts are off the 305, you should be able to get by with them.

Quote:

update- I know the truck ran great before so I went ahead and ordered ACDELCO Part # 2145536

I am glad to see you are using a quality part. These TBI trucks are picky about the EGR operation.

TrueChevyTech · 01-08-2012, 12:39 AM

Quote:

Originally Posted by ChevyTech

I am glad to see you are using a quality part. These TBI trucks are picky about the EGR operation.

Yeah, I also found it cheaper then the competition. I'll post status update in 5-8 days. Of course I chose the freebie shipping option.

**ScottH** · 01-13-2012, 06:23 PM

Interested in hearing ur results, I have a similar situation with my 87.

TrueChevyTech · 01-15-2012, 09:26 PM

Yes just got egr installed runs great. Although sometimes when idling it revs up and throws a check engine light now. But it doesn't bother anything. I would do the apply vacuum to egr either with pump or squeeze the egr and connect a vacuum gauge if it holds pressure it passes the test, then, start the engine and it should bleed off if not the internal bleed valve is bad and egr needs replaced. Also thanks Ron and Chevytech.
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ChevyTech · 01-16-2012, 01:29 PM

You’re welcome, and glad things are going well.

If the check engine light came on it should have a code stored, and you can retrieve the code without a scan tool.

You can search over on the 1988-1998 board where I have posted information on most every problem a TBI can get.

Rattle my cage with a PM if have a question for me, because I rarely ever come over to this part of the message board.

01-06-2012, 10:35 PM	#1
TrueChevyTech Registered User Join Date: Jul 2009 Location: Sioux City, Iowa Posts: 48	Re: Same problem new motor.. Yes the egr has a N, so negative back pressure it is. The numbers on the valve are "dcw 17087198 086 71N" it is 87 half ton 2wd , factory 305, previous owner did a 350 swap, it ran great for 4 years for me then after sitting a couple months it started stumbling slightly above idle. Moving or parked. Posted via Mobile Device

01-06-2012, 11:43 PM	#2
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Same problem new motor.. The EGR should not open at all without vacuum from the solenoid. Sometimes the spring inside the EGR valve gets rusty and breaks. It takes very little vacuum to move the EGR valve diaphragm. Did you look at the link of the illustration to see there is a control mechanism inside the EGR valve? That mechanism is the common failure on these trucks. It has to modulate the opening of the valve. A good test for these is to put a hand vacuum pump on the EGR valve and apply vacuum with the engine off and it should hold vacuum. Leaving the vacuum on it, start the engine, and the valve should close. If it stays open the EGR valve has an internal problem. Look carefully at EGR number, there is a number 17087196 which is common. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

01-07-2012, 12:13 AM	#3
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Same problem new motor.. Do you have one open port on the EGR solenoid? On a negative backpressure EGR solenoid there is one port which is the vent and should be left open but people find a spot they think should have a vacuum hose, so they plug the vent port. The vent port does not have barbs on it like the one that is supposed to go to the EGR valve. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

01-07-2012, 12:20 AM	#4
TrueChevyTech Registered User Join Date: Jul 2009 Location: Sioux City, Iowa Posts: 48	Re: Same problem new motor.. Yeah the numbers I posted are right. I quadruple checked Posted via Mobile Device

01-07-2012, 12:24 AM	#5
TrueChevyTech Registered User Join Date: Jul 2009 Location: Sioux City, Iowa Posts: 48	Re: Same problem new motor.. Yes I also replaced the solenoid, it wasn't holding vacuum very well, vent has filter, I squeezed egr then hooked vacuum gauge, it held at 5 inches (hardest I could squeeze) it also didn't bleed off on start and after warm up Posted via Mobile Device

01-07-2012, 02:02 AM	#6
TrueChevyTech Registered User Join Date: Jul 2009 Location: Sioux City, Iowa Posts: 48	Re: Same problem new motor.. After doing some research the EGR 17087198 would be factory for the 305 motor that was original for that truck. I'm wondering if I should change to a different EGR. This also makes me wonder if the TBI system is for the 305 as well but that would be a different thread

01-07-2012, 02:46 AM	#7
TrueChevyTech Registered User Join Date: Jul 2009 Location: Sioux City, Iowa Posts: 48	Re: Same problem new motor.. update- I know the truck ran great before so I went ahead and ordered ACDELCO Part # 2145536

01-13-2012, 06:23 PM	#10
ScottH Senior Member Join Date: Sep 2002 Location: Hampstead, NC Posts: 8,187	Re: Same problem new motor.. Interested in hearing ur results, I have a similar situation with my 87. __________________ 1963 C10 swb fleetside 1966 GMC G1000 Handi-bus (future project) 1955 Chevy 2 dr. wagon

01-15-2012, 09:26 PM	#11
TrueChevyTech Registered User Join Date: Jul 2009 Location: Sioux City, Iowa Posts: 48	Re: Same problem new motor.. Yes just got egr installed runs great. Although sometimes when idling it revs up and throws a check engine light now. But it doesn't bother anything. I would do the apply vacuum to egr either with pump or squeeze the egr and connect a vacuum gauge if it holds pressure it passes the test, then, start the engine and it should bleed off if not the internal bleed valve is bad and egr needs replaced. Also thanks Ron and Chevytech. Posted via Mobile Device

01-16-2012, 01:29 PM	#12
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Same problem new motor.. You’re welcome, and glad things are going well. If the check engine light came on it should have a code stored, and you can retrieve the code without a scan tool. You can search over on the 1988-1998 board where I have posted information on most every problem a TBI can get. Rattle my cage with a PM if have a question for me, because I rarely ever come over to this part of the message board. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.



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