What engine in my 1987 Suburban.

**kuzano** · 09-13-2009, 02:40 PM

I have two suburbans... 1969 beginning a restore project.

Current issue is my 1987 Suburban. I was told it is a 350. That is in doubt as I am having an ECM problem. I pulled the ECM and the chip code is ADTN which I am told is for a 305. The serial number on the vehicle is 1GNER16H3HF163546. I cannot find a working VIN decoder on the internet that gives me accurate engine information.

My issue is that something is draining the battery and the engine goes into a rough running condition at times while drive and the check engine light goes on. Now the truck will start but not continue to run. I determined that when the truck is sitting, Not Running, with a charged battery, the ECM is too hot to touch. So, I think this is my battery drain, AND my rough running problem. Up until yesterday, the car would idle until the rough running cleared up, but then a few minutes of driving would create the rough running.

So, How do I determine the cubic inches of this engine, and does it sound like the ECM is faulty?

**vncj96** · 09-13-2009, 03:32 PM

Just call the dealership or stop down there with the VIN and they should be able to give you the full inventory for your truck.

**unplugged** · 09-13-2009, 05:45 PM

How about a 5.0 Liter (aka 305 cu in) engine. Letter code H indicates that.
Check out GM's vin decoder here: http://service.gm.com/dealerworld/vi.../vincard87.pdf

**Knucklehead** · 09-13-2009, 07:05 PM

Does or did GM put 305s in there stock vehicals? i thought that was primarily a ford engine? Maybe that is the problem, wrong part? as far as im aware suburbans come stock with.... 1500=350 2500=383 3500=454 i could be wrong but thats seems to be the pattern

**2COR517** · 09-13-2009, 09:34 PM

Wow.

GM built about a bazillion 305s. Used them in sedans, trucks, vans, Subs/Blazers, you name it.

And GM never built a factory installed 383. (At least not that I have ever heard of)

Never heard of a 305 Ford either. 302, yes.

**kuzano** · 09-14-2009, 01:22 PM

It's a 10 class truck, which makes it the low end. And the H code in the serial number does translate to the 305 engine. I'm banking on a short in the ECM as draining the battery and causing fuel metering problems. I almost burned my hand taking the ECM out after the truck had been sitting for about an hour having just fully charged the battery. I had the battery unhooked while charging, then hooked it up and about an hour later decided to pull out the ECM. It was HOT, HOT, HOT!

I thought the engine (I had been told by the seller) was a 350. but the Chip code on the ECM was for the 305. Therefore, I thought the ECM was wrong. However further searching and these posts determined the engine is a 305.

Therefore, I have a correct ECM, but it appears to be failing.

Thanks again folks. Great forum. I'll be back.

Is there a section that deals with the older vehicles, like my Three Door 1969

**2COR517** · 09-14-2009, 01:30 PM

The "10" just indicates it is a half ton. 305s were very popular in them. If you can see the rear of the block, topside behind the valve covers, there are some casting numbers. It might even have 305 cast in it. Get those casting numbers and you can look it up for sure.

**Knucklehead** · 09-14-2009, 05:57 PM

Originally Posted by 2COR517

Wow.

GM built about a bazillion 305s. Used them in sedans, trucks, vans, Subs/Blazers, you name it.

And GM never built a factory installed 383. (At least not that I have ever heard of)

Never heard of a 305 Ford either. 302, yes.

302 was what i was thinking , sorry for the incorrect info, and thanks for the knowledge.The only person i know with a 3/4 ton had a 383 in it .that whats happens when we assume

**ParisDude** · 09-23-2009, 05:14 PM

The block has a 305 cast in the block but hard to find. It's on the passenger side of the engine. I had the 305 in my 88 and it was a solid engine. Only made 195 HP though. Someone told me the 305 has a different harmonic balancer which is hollow inside if you can feel it with your fingers from behind the balancer. . The 350 is solid? What do I know about this stuff!!!