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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 77 cc lb on September 21, 2014, 11:45:51 am

Title: 454 TBI coolant line bypass
Post by: 77 cc lb on September 21, 2014, 11:45:51 am

Hi, I have an 88 Suburban with the 454 TBI. I am replacing all the gaskets (TBI, intake and valve covers). I don't want to risk having a coolant leak in the back of the TBI because I didn't put it back together right. Is it possible to do a bypass line around the TBI or is there a trick to putting the line back in? Thanks for any info!

Title: Re: 454 TBI coolant line bypass
Post by: Captkaos on October 09, 2014, 10:24:40 pm

There shouldn't be any coolant going to the TBI on a 1988 454 motor...

Title: Re: 454 TBI coolant line bypass
Post by: 77 cc lb on October 15, 2014, 02:43:23 pm

There is a heater hose coming from the intake manifold that goes into the front of the base plate of the TBI. And then at the back of the base plate there is a hose that goes to the heater core. The clip that goes in the back of the base plate is messed up and I am having trouble finding another one. I was wondering if I could just bypass the base plate and go from heater core to intake manifold?

Title: Re: 454 TBI coolant line bypass
Post by: bd on October 15, 2014, 04:43:00 pm

Can you post a clear pic of the clip?  Some of the retainers are available by themselves; some are available only as part of a complete fitting.

Title: Re: 454 TBI coolant line bypass
Post by: 77 cc lb on October 17, 2014, 06:34:19 pm

Hey bd, I think I might be missing 1/2 the clip! Looked into a TBI rebuild, but showed nothing.

Title: Re: 454 TBI coolant line bypass
Post by: Engineer on October 17, 2014, 06:55:39 pm

I wouldn't bypass the base plate.

Without it in the winter you will have drivability issues because the heat helps atomize/vaporize the fuel/air mix.

Title: Re: 454 TBI coolant line bypass
Post by: pholliday1 on October 17, 2014, 10:50:33 pm

The Tbi should have coolant going to it. I also recommend not to bypass it. In 1987 the line is threaded and finding one of those lines is near impossible. However in 88 they (GM) started using a quick disconnect  like you describe. GM had a very difficult time trying to keep these vehicles from surging at Idle. Unless you live somewhere that's always Sunny and 75 I would consider keeping it on the engine. As of right now I do not have a source for you, for that clip if you do end up finding one report back so the rest of us can be aware of it.

Title: Re: 454 TBI coolant line bypass
Post by: bd on October 18, 2014, 12:34:30 am

Assuming a 5/8" hose, look at Napa #NOE 7304943 quick connect fitting (http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Heater-Hose-to-Heater-Core-Connector/_/R-NDP7304943_0418528579).  Or for the clip by itself, Napa #NOE 7304947 (http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Heater-Core-Connector-Clip/_/R-NDP7304947_0390050151).  Napa is probably not the only source.  Take what's left of the old part with you and compare it to the part numbers provided.

Title: Re: 454 TBI coolant line bypass
Post by: 77 cc lb on October 19, 2014, 03:54:10 pm

Thanks for the info guys! I was debating to do the bypass or not. Thanks to bd for coming with part numbers, will head to NAPA tomorrow.

Title: Re: 454 TBI coolant line bypass
Post by: 77 cc lb on October 20, 2014, 06:24:11 pm

Hey bd, was the right clip, but after shipping from out of state, not worth it . I stopped at Lowes plumbing dept and made my own new connector. Thanks again for the info!!!

Title: Re: 454 TBI coolant line bypass
Post by: bd on October 20, 2014, 07:10:33 pm

That is amazing they don't stock it.  Nearly every parts house I've visited for that clip, and clips similar to it for other applications, has had them!  Glad to hear it's resolved.